This game feels like it was one revision short of being production-ready; as if it was the final rough draft of a good college paper. It has all the elements for a really good stealth/action game, but it needed one more round of polishing before it's there. Actually, if the developers released a patch, I think that's all it would need.
The biggest problem I have with this game is with the model movement and positioning. For example, if I'm trying to sneak along, while I'm walking on a catwalk system (which you do several times in the game), and I try to carefully adjust my position, it's just too easy to fall off. Why? No, it's not all user-error. If I'm facing one way and try to carefully turn the other way, the model has to move, almost jerk in the direction she's facing before she actually turns around. This extra forward movement caused me to fall off several times! >:( There are also scenes where you have to carefully move around while trying to avoid laser motion/heat detector beams. This annoying extra movement has also caused me to hit those beams, which of course gets me killed almost instantly.
Another gameplay problem is the aiming...you can't aim your weapon yourself! Well, that's not entirely true, but the only way to aim is to toggle the right trigger until you're pointing at the baddie you want to shoot. But if you're on a catwalk, there's simply no way possible to aim down at the baddies below you! What?! Why not??!! In most other games you can use the joystick to move your crosshairs around and aim at whatever/wherever. But no, not here. I don't get it, unless we're not supposed to have that kind of advantage. But this IS a stealth game, so what's the point in having a weapon, sneaking up on a group of baddies, and not be able to use it??
Another short-coming, though it's not a gameplay issue, is the enemy AI. Most of the time these guys are horribly stupid! At some points you can be seen by someone, but if you run the other way and turn a corner, he'll forget you were there. Or sometimes you can just crouch and wait several seconds and again he'll forget you were there. At other times you could hang from a catwalk and dangle right in front of the bad-guy and he won't even notice! It makes sneaking around easier, but it's still laughable.
One more complaint:
There's not much interaction allowed with the environment. You can push and pull some objects to help climb up to certain places, and you can grab only a few objects to use as weapons, but not many. Much of the rest of the environment is "just there"; you can't do anything with it. I kept wanting to open this door or pick up this thing or move that thing. But nope, couldn't do it. The bad thing about this is that it makes the world less believable and seem too sterile.
Even though I've bashed it, the game does have its moments, and there were times when I had fun figuring out how to pass a level. The special attacks (press and hold X) are pretty neat, and they allow you quietly eliminate the enemy. These moments, plus the storyline, kept me going to the end. If you're a fan of the game, and if you can deal with the control issues, you may want to give it a try. The story and cut-scenes are worthy of a good TV episode, and the graphics are acceptable. It's just the gameplay that too often gets in the way.