I played it for about an hour or two and wasn't too impressed. It's basically Gears of War continued, with a meh storyline and crappy dialogue.
There were a few moments were I was genuinely impressed, but for the most part it was subpar for GoW. I actually enjoyed GoW as a game and found the story fun. GoW 2 seemed to be nothing more than a giant set up for a conclusion. If, and only if, they manage to make HUGE fireworks go off in the 3rd gears with the strings they opened with the story in the 2nd one, then I'll be impressed. Otherwise, I'll wonder how a focused game wandered so much.