Hurr, I don't know what to expect, but I can say what I want and don't want:
Want:
+Dante as a playable character for the entire / (most of the) story
+Similar play style to DMC3
+More weapons, both melee and guns - more interesting / cool guns. I found myself really just relying on the handguns and not really using the others, sometimes shotgun, sometimes rocket... But I'd like to see maybe 10 sword/melee weapons and perhaps 6 or 7 guns. That'd make my day! But I'd be happy with 6 of each. But it really depends on the quality of each weapon, I don't want 5 ****ty weapons and 5 cool ones, I might as well just have the 5 cool on their own.
+Same rock/metal/dark theme to the game
+More cool moves / stunts for Dante to pull off
+Would be cool to play as another character, but that's not top of my list
+Better continue system. It was getting better in DMC3, but still wasn't perfect. It did make it hard though, which was cool. If they just let you save constantly, that'd be way too easy. But they could have moderately hard check points, so you don't have to do the ENTIRE level again perhaps... but I dunno. It wasn't that much of a problem for me.
+More interesting way to get more orbs and power up. Powering up was really awesome, but just doing level 1 over and over wasn't that cool. Maybe every 5 levels they could give you a new straight-out fighting level like level 1, but tougher. So for the first 4 levels, you'll be going back to 1 to power up. Then you get to level 5, and you can use that to get more orbs, it has toughter enemies and you can earn orbs faster there, and it'd just be a change of scenery. The amount of times I played level 1 on DMC3 was obscene. Then they could do another at stage 10, and at stage 15. Cool.
+Should be able to GRAB some of the enemies. Grab skill could be increased, so you can grab larger and larger enemies. I want to see Dante doing suplexes and DDTs and powerbombs, how awesome would that be? It'd add a whole new dimension to the game I think, if done right.
+the same level of difficulty, and extreme boss battles! Oh yeah! I like to face a boss first time and think 'Damn there is no way to win!!' and gradually get better, that is awesome. I don't want it to be easy.
DON'T WANT:
-Vehicles (someone else suggested this) I really don't think it'd work in the DMC world, it'd just be a lame kind of sub-game thing and wouldn't fit
-Collecting keys from obscure places and walking around an empty map for minutes on end. Also it should be clear where the destination is to save the tediousness of wandering around - again, in an empty place. Or give better clues on the larger levels of exactly where you're meant to be going. Just walking in DMC isn't fun in my opinion, things don't need to be so spread out.
-Platform sections, I don't want ANY, the engine is not built for it and it's just frustating.
-'Simpler' controls, as have been hinted at. I think the controls are fine and allow a lot of freedom. To 'simplify' them, I worry it would restrict what you can do at one time.