I feel that this game's story is very well-told and well-scripted. It is hard not to feel bad about things happening in the game, especially when you are playing the last chapter. The game's plot twists can be a bit confusing, especially if you have not watch much time-travel movies like Back to the Future movies or time-travel games.
In many ways, the ending is left to the player's interpretation. It can be either bad or good. However, I believe that the game has happy ending.
There are not much games that have good storylines this year. I predict that The Last of Us and Beyond: Two Souls may have radical and mindblowing stories that can compete BioShock Infinite's story, but I will reserve my judgement until I play both games when they are released.
Did you feel like the game "spoon fed" you the details in the last 20 minutes or no? Vigors weren't explained at all, unless I missed something. The game and story is extremely good no doubt about it.