I played through it cold on Hard and found it a little challenging, especially the boss battles and few Handymen fights. I really dislike the vigors (ie, Plasmids/Tonics) of the game so it meant using the guns most of the time, of which you can only carry two at a time. However, I did enjoy the whole tears aspect of the game, which did enhance the gameplay a bit.
Atmosphere-wise, Columbia isn't on par with Rapture, but that's just because Rapture had a much darker tone than Columbia did. Columbia is still very grand and beautiful to look at. It just didn't immerse me like Rapture did.
I felt ho-hum playing as Booker, who just felt like some skilled soldier to me. Elizabeth was a very good character though and I grew to care about her and her relationship with Booker.
The only reason this game gets an 8 though is the ending, which was mindbending to say the least. It took a few recaps online to full grasp it and I can honestly say it's one of, if not, my favorite game endings. Looking back on the game while knowing the ending makes the game better alone.
-Some gameplay elements
-Lack of 'crazy' events (until ending)
I thought about giving this an 8/10 but I feel that it's not fair to judge a game based on it's predecessors.
Bioshock: Infinite is significantly different from Bioshock 1 and 2, both in better and bad ways. Overall, the game is amazing and has an incredibly complex story, great voice work, graphics, locations, gameplay, and more. The main problem with my perception of the game is my experience with Bioshock 1. I expected this game to be dark, scary, immersive, and ominous like the first one, but instead I get a game that is, for lack of a better word, "brighter". In concept, a floating city sounds cool, but once you get over that fact it's still just a city with rooms and stores and streets. It can never compare to Rapture. Also, most of the powers you get are obscure and not very "bioshocky" (in my opinion).
HOWEVER, even with all of that said, Bioshock: Infinite is nothing short of amazing. Just not what I expected.