So Dead Rising 2 is a zombie-slaughtering good time. It's not exactly an huge evolution from the first game, but if you really enjoyed the first game, you can expect more of the same fun.
With Frank West out of the picture (lololol), the photography aspect of the game is gone, replaced with (in my opinion) something better and more fitting. Chuck hasn't covered wars, you know, but he does get to combine all sorts of items into incredibly fun and dangerous weapons. Dynamite and a fire extinguisher creates a freeze bomb. Dynamite and a chunk of flesh creates a timed bomb that attracts hordes of zombies to it. Attach a machete to the rotors of a toy remote control helicopter and... well, you can imagine. It's the primary feature of the game that really separates it from its predecessor.
Co-op is a lot of fun, but strangely, it's almost not as good as I'd always imagined it would be. Having the extra set of weapon-swinging hands along for the ride is a definite benefit, and the drop-in co-op is executed very well, even if it is clearly tacked on. But it's not the kind of co-op where it feels like it's so good you need to play the game through with a buddy. It's more like, play the game, if a friend drops in, cool. If not, cool.
If the game has the same number of endings as the original, I think it'll definitely warrant a second play-through.
I also want to point out that it is October, and thus it is National Breast Cancer Awareness month. About one in eight women in the United States will develop invasive breast cancer over the course of her lifetime. Awareness is absolutely the biggest key to prevention. Please make sure your loved ones are performing self exams. Ask your wives and girlfriends if they've had a mammogram recently. Save the boobs, people.