The very definition of what every superhero game should be.
The game is set after the events of Batman: Arkham Asylum (which was also a great game). Joker is now in the city of Arkham, reeking havoc on everything and has poisoned Gotham City, Batman, and himself. It is up to Batman to find the cure. We also meet the face of the Riddler for the first time. The story is very smooth and has quite the twists and turns in it.
The gameplay is even bettter. Combat is a load of fun when you learn everything and stealth is phenomenal, you can do almost everything you've seen in any Batman movie when Batman takes out a room silently.
I would recommend this game to anyone looking for an awesome challenge but is also amazing along the way.