I'm about 20 hours into it...the game is downright fun. The differences from 1 ring true, but i'm having a good time. Other than that, the graphics on PC are kinda disappointing, in my opinion. They'll be raved over on the console, but it looks very much like a console port to me. near textures, like faces and personal armor, are generally very good. Other than that, it seems to fall apart. The game NEEDS AA badly, but i haven't found a way to implement it. That said, my system runs full settings @ 1680x1050 @ 40fps+...so it isn't exactly taxing.
Someone said something about the control scheme...it works very well with mouse+keyboard. It takes a little getting used to, and cover to cover doesn't REALLY work as well as it should IMO, it adds a little bit of freedom to combat, but i find myself stuck against a wall with an enemy's shotgun in my gut as often as i did in Gears, but maybe that's just me. After some practice, combat and ability use will flow smoothly and easily.