Ok, so I've spent about 5 hours with this game, tried m.p briefly, and here are my thoughts:
Visually stunning, endlessly fun (I love how I can choose to turn this into mgs fps or rambo on steroids), solid multiplayer that isn't nearly as bad as people tout it to be imo, interesting story, brilliant score by hanz zimmer. Heh as you can see, I'm not going out of my way to hate on anything, and this would be one of my favorite games ever if it weren't for one thing. As has been said before, the A.I is pretty damn bad. When I heard reviews discuss this, I thought to myself, 'ok they're definitely blowing this out of proportion', but unfortunately they weren't... Don't get me wrong, at least a miajority of the time, the A.I is intelligent, tactical and powerful, but at least once (but probably 2-3 times) per area containing baddies, I'll see someone walking into a corner endlessly, standing still in front of me even when I uncloak, or fidgeting in place like he has parkinson's disease (sorry bad joke). Other times the A.I is practically psychic, and will see me from over 1km away when I am 95 percent covered by something, or they will see me through an incredibly thick hedge that it would be unrealistic for it to happen. Aside from that, though, the game is essentially the perfect first person shooter, and I definitely recommend it.