A crowning achievement in the BioShock series.
Infinite takes all of the positive aspects of the original game, refines them and adds several new dimensions, particularly in the gameplay.
Just like in the first instalment, the storyline does an incredible job of keeping you interested. I don't want to give any details of it away, as I strongly recommend discovering it on your own. Suffice to say that Columbia, although somewhat contrasting to Rapture, is a world of stunning visuals that you will enjoy loosing yourself in. The character development is very well executed and the story will have you discussing and thinking about its ramifications long after you've finished the game.
Furthermore, the combat has come along in leaps and bounds from the first game. Plasmids are replaced by Vigors, which are essentially that same thing (super powers emanating from your hands), but can be combined in some imaginative ways. There are some incredibly fun and interesting aspects which include zipping around the combat area on an overhead skyline, jumping off to crush your enemies and calling upon stage-dependent temporary aids (such as different guns, cover and automated gun turrets). Again, not wanting to give anything story-related away, I won't go into the details of the combat mechanics!
I can't recommend this game enough. Although it isn't perfect, it comes incredibly close. I think BioShock Infinite highlights how far gaming has come in the last 5-10 years in terms of a multimedia art form; beautiful aesthetics, engrossing story arc and entertaining gameplay - go out and buy it if you haven't already!