I just finished the game today after being sidetracked by many games (Saints Row: The Third, Assassin's Creed: Revelations, etc...), and I am glad and proud to say this is a great game.
Story
This game place takes during the Age of Fire. You, as the chosen Undead, will leave your asylum and embark on a journey in Lordran. While you are there, you will encounter various things and dangerous monsters that will stop you from fulfilling your destiny as the chosen Undead.
The storyline is very simplistic in manner. The prologue provides very brief explanation on the game's history, and it actually surmises everything that has happened to the game's world. If you want to know more details about the game's mythology, talking to NPCs will certainly provide you more details as to what happen in the game.
Some NPCs have their own sub-plot in the game, which can be followed by talking to them or doing certain actions to advance their sub-plot. Their sub-plot is not exactly important to follow in the game, but some can provide you interesting information about themselves and may even reward you with a rare item.
Although this game have simplistic story structure like Demon's Souls, I prefer this game's storyline as it is much easy to relate and follow. This is because the game's mythology is quite fascinating, such as the history of Undead, Gwyn's mystery, etc. If From Software have paid a bit more attention to the game's storyline, I think the storyline will improve and will be much more developed.
Gameplay
Story

You are the prophesied Undead that will leave the Undead Asylum and ring the Bells of Awakening in Lordran.
This game place takes during the Age of Fire. You, as the chosen Undead, will leave your asylum and embark on a journey in Lordran. While you are there, you will encounter various things and dangerous monsters that will stop you from fulfilling your destiny as the chosen Undead.
The storyline is very simplistic in manner. The prologue provides very brief explanation on the game's history, and it actually surmises everything that has happened to the game's world. If you want to know more details about the game's mythology, talking to NPCs will certainly provide you more details as to what happen in the game.
Some NPCs have their own sub-plot in the game, which can be followed by talking to them or doing certain actions to advance their sub-plot. Their sub-plot is not exactly important to follow in the game, but some can provide you interesting information about themselves and may even reward you with a rare item.
Although this game have simplistic story structure like Demon's Souls, I prefer this game's storyline as it is much easy to relate and follow. This is because the game's mythology is quite fascinating, such as the history of Undead, Gwyn's mystery, etc. If From Software have paid a bit more attention to the game's storyline, I think the storyline will improve and will be much more developed.
Gameplay

Any experience of playing Demon's Souls will come in handy in this game.
At the start of the game, you are prompted to choose a class and the appearance of your character. Strictly speaking, choosing any class will do since your character can learn any magics of equip any weapons. What makes choosing a class important is your starting stats and equipment. Each class have different starting stats and equipment for you to use, so it is wise to choose which class is best suited with your play style. For example, if you favour melee attacks using a sword or axe, using a Knight or Soldier is the best choice, since they have the necessary Strength to wield those weapons efficiently. If you do not have the necessary stats required to use a weapon, then the effectiveness of the weapon will be reduced and you will not able to use it properly. For example, you have 10 Strength, but the axe is heavy and requires you to have 15+ Strength. As a result, you will not be able to use it properly and you will have a long recovery time after swinging that particular weapon.

You can use any weapon to fight your enemies. Choose appropriate weapons that suit your playstyle.
Like many other RPG games, you have to attack your enemies to defeat them. Defeating them nets you Souls (currency in the game), weapons, armour parts, or even upgrade materials. You can use a wide array of weapons, such as longsword, spear, axe, etc. If you use a weapon on your right hand, you can use either normal attack or strong attack. Normal attack is quick, and consumes less Stamina. String attacks are slow, more Stamina consuming, but stronger than normal attacks. Every special movements such as rolling, sprinting, blocking, or executing an attack will consume your Stamina appropriately. You can also wield your weapons two-handed, and the attack power will increase, at the risk of being opened to attacks. If you equip light shields on your left hand, you can use it to block attacks. You can also use it to parry your enemy attacks and use a riposte on it. You can also do backstabbing when you are at the enemy's back, or execute a plunging attack when you fall from a high place.
Each weapons have their own pros and cons, as well as move sets. For example, an axe has high attack power, but very slow to use and long recovery time. Experimenting on each weapons will tell you whether this weapon is good or not. Some unique weapons have their own unique ability, such as fire enchantment, etc. This can be achieved by upgrading your weapons.
Each weapons and armour parts have their own durability, and will eventually be broken if their durability is emptied. Repair them to have a safe journey in this game, as well as upgrade them if you have the necessary materials to do so.

Non-linear progression. Check a guide or walkthrough if you are stuck somewhere in this game.
This game provides non-linear progression, but all in all you will achieve the same objectives in the end. The objectives in this game are quite vague, and it would be best if you talk to the NPCs often to know what you are supposed to do next. Alternatively, you can check walkthroughs or read a guide to know where you should proceed next.
Progressing in this game is fairly hard, as most areas are filled with monsters to fight with, deadly traps, and tough bosses. In most areas, you need a key to proceed to your next objective. The key will describes where the key supposed to be used at, and it is recommended to read their description at your menu.

Bosses are tough, and should not be underestimated.
Every enemy in this game is mostly unique, with their own attack patterns, behaviour, appearance, stats, and skills. Learning on how enemy attacks and moves is important for your survival, as deaths in this game is fairly common. Each of them have their own weaknesses, so exploit their weakness by using a variety of weapons, such as Fire weapons, Lightning weapons, etc.
Bosses are the highlights of this game, as well being as the challenge to stop you from progressing in this game. Each bosses have their own strengths and weaknesses, and their own attack behaviour. For example, Taurus Demon is strong and fairly resilient, but has slow attacks and can be dodged properly by rolling. No matter what you do, do not falter if you have been killed by the bosses, since they are meant to be tough, and each bosses requires a certain strategy to beat them effectively.
In this game, stats is quite important. You can increase your stats by spending Souls. Souls act as the currency in the game, and can be obtained by killing enemies, killing bosses, use the Soul items, etc. As you increase more and more of your stat points, the Souls requirement to level it up will increase it as well. This applies to every stat points in the game, as all of it links to your Soul Level. For example, if your Soul Level is 20, the required Souls needed to increase a stat is 2000 souls, regardless of any stat. In other words, although you have increased your Strength to 30, the required Souls to level up any other stats will increase as well as your Soul level will keep increasing.

Learn all three types of magics in the game to defeat your enemies: Sorcery, Miracles, and Pyromancy.
Regardless of any class, you can learn magics by having the required stats to learn it. To learn Sorcery spells, you need to have the required Intelligence points, and as for Miracles, you need to have the required Faith points. Pyromancy does not relate to either stats, as you can purchase directly from certain NPCs. Like many other things in the game, most spells in the game are bought by spending Souls, or finding them on dead corpses or treasure chests.
Each category of spells have their own uniqueness. Miracles mostly focus on healing and support spells based on your Faith stat. Sorcery mostly focus on offensive spells based on your Intelligence stat. Pyromancy have a mix of offensive and support spells based on how powerful your Pyromancy Flame. All spells have their own number of uses. Weaker spells generally can be used more often, and stronger spells have more limited usage.
In order to use either of these spells, you need a specific equipment in order to use it. For example, you need a catalyst to use Sorcery spells, and you need a talisman to use Miracles spells. Be mindful that you can can only equip a certain number of spells at your spell Slots, and you can increase it by spending Souls on your Attunement stat.

Bonfire is your checkpoint, grinding source, and rest area.
A great feature in the game is the Bonfire. Bonfire recovers your HP fully, cures all of your status effects such as poison, and recovers spells' usages. It is best if you utilise the Bonfires to the maximum as they will be very useful in the game to save your progress, or to heal yourself. One thing should be noted that whenever you use a Bonfire, all enemies will revive at their original locations, regardless of them being dead or alive. All of the lesser enemies will respawn, but certain strong enemies such as Black Knights will not respawn after being killed. Utilising Bonfire to farm Souls and materials is very important in the game. The general rule in this game is that you will not progress far if you don't have high stats or good equipment.
Whenever you quit the game from the menu, you will always reload your save wherever you last quit in the game. Keep in mind that that you will lose some progress if you quit the game abruptly or turning off your console without quitting the game.
You can join a group of Covenants for various bonuses. Joining a Covenant will reward you something, and it will allows you to have various bonuses, such as when playing online. You can change your allegiance to Covenants anytime, but some of it are missable without fulfilling certain conditions.

Get used to dying in this game.
Dying in this game is common, and should not be taken neither lightly or hardly. By dying, you will know where you should avoid and try to correct your mistakes. Sometimes, you might die because of accidentally roll into a death trap, and you will be punished for that carelessness with your death. If you have died, you will lose all of your Souls and Humanity points. Humanity allows you to do many things, such as revert to Human form, kindle Bonfires to obtain more healing items, etc. You can retrieve all of your Souls and Humanity points by touching your bloodstain where you have died previously. If you have died again, those Souls and Humanity points will be lost permanently, so be careful.
You can also play this game online with your friends. You can put a Summon Sign to make yourself available as a Phantom to be summoned to fight a boss in a particular area. Defeating a boss in this manner will reward you Humanity. Conversely, you can also summon other players to help you in fighting the bosses in the game as well. You can also invade another player's game and try to kill him/her for Humanity, and you can be invaded by other players for the same purpose. The online playing is improved than Demon's Souls, and you will rarely lose connection with other players unless you have slow Internet connection.
The gameplay is nearly perfect. Great combat system, hard difficulty, deep learning curve, great challenges, excellent boss fights, non-linear progression, lengthy playing time, and most of all, provides great satisfaction when defeating tough bosses. One should be reminded that this game is not intended to play for those who likes easy games and non fans of RPGs. The process of playing this game is mostly trial and error. Once you get used to the gameplay system, you will find the game more easier to play with. This game is an essentially hard and challenging Action RPG game, no doubt about that, and it will mostly caters to players who are RPG experts or for those who are looking for a challenge in playing games.