Good news everyone! The game is as good as it looks. It's not simply a beat'em-up. Several previews have gone up and the details are as follows:
Story: The story/script was written by famed Batman writer Paul Dini, co-creator of Batman: The Animated Series.
Voice actors: As we all know, Kevin Conroy and Mark Hamill reprise their roles from Batman: The Animated Series (and others) as Batman and Joker respectively. Well, Arleen Sorkin will also be reprising her role from Batman: TAS as Harley Quinn, and possible some others.
Gameplay: There's a great deal more to the gameplay than meets the eye. It's a stealth-action game ala Metal Gear Solid/Splinter Cell. There's also a Metroid Prime-style detective perspective where you go into an infared type mode and can see fingerprints, clues, scent trails, how many people are in an area and how many of them are hostile, etc. So as much as the game involves stealth action and regular action, it also involves thought.
The mechanics of the game are context sensitive so you can take on a group of thugs head on, or use stealth to pick them off from the shadows/etc. In the context of a location you could bust through a grate or slowly and carefully remove the grate so not to alert anyone to your presence. And so on. Batman's gadgets will be available and at his disposal as well.
There are also neat little nods throughout the game. Two examples of this would be the fact that as the night wears on (this being the longest night of Batman's life) his face will grow more and more stubble. And your suit can be damaged, so if someone, for example, shoots bullet holes through your cape those holes will stay there and you'll need to factor them in when attempting to glide.
So there you have it, this is no simple brawler. It's a multi-faceted stealth-action experience that pays homage to Metroid Prime, Metal Gear Solid, BioShock, and Splinter Cell in many of its gameplay mechanics, has a great many nods to the comic and DC animated universe continuities, and is a game the developers hope will stand on its own.