Well I've played it for about 1.5 hours and I'm pretty happy with it.
First off, given my rig in sig (Opty 146 @ ~2.4ghz, 1.5GB PC3200, 7800GT @ 460/1150), I have to turn the graphics way down, and it looks like a game at least a few years old. After seeing the Unreal Engine screen, I figured it would scale a lot better, or at least look decent given how low of fps I get. 1024x768, mid to low details. Gah, and no WS support (1280x800 would be possibly do-able framerate wise). So that is very disappointing, considering that my rig is fairly decent... certainly better than most PC gamers. Sucks that it requires such high-end systems, and a SM3 card, because surely they can't expect much sales at all given they left out a huge % of PC gamers (or even worse, people who buy it but can't play it, and can't return PC games).
I am still in the first level. It is quite long, fairly hard even on normal, and checkpoints are far away. I am on the mission where I am about to enter the mines and take that tango alive. So I don't know how the framerate and graphics are once you get to Vegas, but I'd imagine it won't run any better. I mean come on, I got a decent rig, have to run at very low/crap settings, yet I'm stuck with somewhat low fps at times and pretty bad graphics. GRAW was similar in this aspect though... just not very optimized games IMO. Considering games a couple of years old (Source, BF2, Guild Wars) that run maxxed, look spectacular, and run on lower-end rigs just fine.
Anyway, I think the gameplay is good. It's not too tactical, which turns off a lot of people. I am playing quite tactical and very slow though, which I like doing. I haven't played much RB6 Raven Shield nor Lockdown ever, but I should probably give those a try sometime later, and compare to Vegas to see how much tactical play I like most.
Weapon selection is nice. Cover is done well. Teammate AI is pretty decent, though I generally leave them a little behind since they have a easier chance of dieing (game over) than I do. Enemy AI is decent. Some bad parts, but overall I like it. Different enemy placement is nice, as well as basic covering, flanking, etc.
Squad control is quite easy and effective. Love scoping out rooms with the snake cam, placing my guys at the door, then we rush in at separate doors at the same time.
So, lots of people didn't like the game, but I think it's pretty damn good, and definitely worth it, IF you have the rig to run it. And would like a somewhat tactical (you can run and gun, or take it slower and be more tactical) FPS. Will probably update my opinion once I get another level or two into the game, but it's pretty positive right now. Have not yet tried multiplayer.
edit: I have a 360 controller for my PC, and seen it had native/built-in support, but in a somewhat tactical game like this, even if I spent time using the 360 pad, I bet there's no way in hell I could shoot and move anywhere near as well as kb+mouse which I have a ridiculous amount of years/hours playing PC games.