What a wonderful First Person Shooter. First--the Single Player takes a solid 20 plus hours (indoors, outdoors, in the air, and on) to play with the use of Slow, Reverse, and Stop time and your ability to literally gib--and reverse, gib and reverse, and play with your enemies. The game is technically astonishing with a depth of dynamic shadows, incredibly detailed environs and a butt-kicking (no-slow-down) frame-rate. Then when you get great at it--you can play it again against AI that is better than first rate and makes great use of your ability to confuse them (temporarily) with the time powers.
The Multiplayer though?
It puts other games to shame. I have never seen more game types--faster play for up to sixteen, and had such fun with everything from Rocket Arena to Team Deathmatch. There are new modes like King of Time (get the player with the time powers and you become the target) and Meltdown Madness where you use your four time grenades (Multiplayer has weaponized time bubbles) to slow the coolant to your enemies reactors. This is more fun than Halo 3, Half-Life Orange Box, and Bioshock combined (and actually longer than the new content in the three of them if you include multiplayer. Highly recommended.