The Critics are right, but it is a fun Shooter...
The graphics are great, and the sounds are awesome. You feel very much "in" each battle with your resistance buddies. The weapons are pretty cool (so far) but as I said before, be prepared to reload... a LOT. The explosive weapons (grenades, arrows, etc.) are very effective, but are in short supply sometimes. You find yourself waiting for your suit to recharge in between short 2-3 man battles, and hoping they don't charge you while you're vulnerable.
The AI seems to be alright. They take cover and use "group" tactics at times, so they're not mindless by any means. However, they can be difficult to take down if you're more than 50ft (scale) away and you usually resort to time-shifting to take 'em out at close range; which may be the point.
The levels (so far) seem linear. Point A - Point B - Point C, kill, don't die. I've only come across a couple of little "puzzles" where you use your suit to slow or stop time in order to get from point to point; and they're pretty obvious. A couple of times, I wondered why my resistance buddies went in one direction while the game forced me to go another alone. Shouldn't I be fighting the good fight WITH them even though I'm completely out of place?
The game seems fun/playable so far, but with little replay value. I think they'll probably concentrate on the Multiplayer aspect more than the single player. That seems to be the way PC FPS's are going these days. Even with the 1.01 patch, the game has a lot of flaws in its execution; however it is a fun shooter, and the ability to control time itself makes the game worth it.