With my experience with the game, I say that it is phenomenal. You could even compare it to Assassins Creed and you wouldn't know which would win. But to be fair to warn you that this game is not meant to be played by really oblivious gamers. I might even call myself a really dumb gamer at times. But the twists and turns (and complications) are very interesting. You will always be drawn into it more and more as it goes on.

Story: Of course, you are Batman, but if you have a certain dlc you can play as Catwoman in a whole different storyline. But since I didn't try to play as Catwoman yet I won't touch on the topic too much. So in a nutshell, Batman is captured by Dr. Hugo Strange as Bruce Wayne who was on a campaign to get rid of Arkham City, yadda yadda yadda, and you have to find a cure for yourself because the Joker infected you with his infectious blood. There will be many twists and turns but if I tell you about them, it will spoil the fun :D

Game Mechanics: The way you smash the faces of your enemies and the various amount of gadgets you get always amuses me. It feels very authentic to the Batman franchise and way you level up and go on quests causes a rpg feel to the game. By leveling and going on side missions causes you to find more information on other villains (sometimes), like the side quest with finding telephones. It gives you more background information on that one villain. Also it is just plain fun to grapple your enemy with the batclaw and then piledrive them into the ground with your elbow.