Definitely deserves the rave reviews people are giving this.
Cons ; Windows Live yukkiness, combat is a little too simplified for my taste, playing the game in detective mode really takes away from the great visuals, this game was a pain in the ass to get installed at least for me.
Pros : Stealth action, gadgets, realistic game physics, awesome visual and aural atmospheres and great voices. Really puts you in the bat shoes.
To explain my negative towards combat I'll admit its probably a bit of personal taste. I'm not a big fan of combo systems that rely on stream chaining the main hit button. It feels alot like what KOEI did with dynasty warriors latest releases. Keep hitting with the same button, and the more you hit the cooler the animations get. That doesn't feel like hitting combos to me. You do get some pretty cool controls for the gadgets though. the batarang, and grapple have some nice combos that require some skill. I think I would have gave the game 9.5 or 10 if the combo system was just a little bit more skill based.
The rest of the controls are great when interfacing with the environment and objects and using stealth.
Overall the game is fantastic though. The combat is not all the big of a deal, because in reality you are batman not Jackie Chan. Hide in the shadows and invisibly take out foes is really the heart of this game, I think. Anyway, I dig it.