Engaging and full of attitude
Starting off, you have nothing but your fists to protect you and to quietly incapacitate unwary guards. The stealth is incorporated extremely well, and the hand-to-hand fighting is extraordinary, though the controls could be a bit smoother in this area.
CoR is very original. I haven't experienced anything like it in a game. I got a similar feeling to when I played the original Half-Life (and the sequel, for that matter). It's full of memborable moments. One such moment is when I snuck up behind a guard who was standing on the edge of a concrete drop, expecting to execute the nifty "sneak-up-and-choke-hold-then-break-his-neck" combo. When I went for the attack, Riddick instead simply nudged him off the cliff. I watched the guard flail and scream as he plumeted to the concrete far below and bounced in a very satisfying way.
The graphics are amazing. It looks like it robbed the Doom 3 engine (and I thought it did until I couldn't find any credit given to Id Software anywhere). But be warned - also just like Doom 3, this is a serious hardware killer. I'm playing on an Athlon XP 3400+ equivalent with 1Gig DDR400 and a Radeon 9800 Pro 128mb. To get a playable frame rate with shadows and a little AA, I had to play at 800x600 with everything knocked down to half.
Quite simply, this is an immersive experience worthy of playing. Only a few bugs and control issues are what keep me from rating it higher.