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)