Just finished the game myself.
If you had asked me what I thought of the game 50% through I would have had mixed feelings about it, and probably wouldn't give it higher than a B. But luckily the 2nd half of the game is so very A+ quality that in the end, I can defintely say I enjoyed Riddick very much.
The major problem with the game is that the graphics look like shit ALOT in the early areas of the game
The low-res jaggie problem is terrible in cutscenes and terrible in some of the early areas (such as the big open area at the prison, or the landing pad). But then after about 30% in, the low-res issue pretty much disappeared for the rest of the game minus a spot here or there and then the game was looking absolutely gorgeous. It's like they got 3 months in on development, realized the low-res problem, and learned to work around it for the rest of the game but didn't bother going back and re-doing the early work that had been finished. The demo was all from this early area, so unfortunately most of the demo looked bad
Overall I couldn't give the graphics higher than an 8 IMO because there are just too many parts where they look like a 2/10, despite the rest looking like a 10/10. But once you get half-way you're looking at straight 10/10 graphics which is very nice indeed ^__^
My other problem was just the lack of polish with the game. When you're going up or down elevators the screen freaks out and hops up and down as if the engine doesn't know how to handle fast vertical movement ^^;; You also have the sometimes funky hit detection where you reach out and snap the air and then the guy 2 feet to your left has his neck snap and falls down :\ Then you have the loading which for the most part isn't too long and the areas are pretty big. But then you have parts like the ring fighting where you have to talk to guy in area A, walk through loading screen to area B, talk to guy in area B, walk back through loading screen, talk to guy in area A. Repeating this 4-5 times got a bit annoying and made me wish the people who I needed to talk to were close enough that I didn't have to walk through loading barriers all day :\ Same problem of loading and lots of walking plagued most of the one section that was around the 30-50% mark of the game.
Luckily after that 50% mark the game drops all the backtracking, sub-quest within sub-quest within subquest BS and just turns into a straight stealth/action edge of your seat FPS and man is it good. I played almost all the game stealth style with breaking necks and such, but for a few parts near the end I tried playing action style tossing grenades into rooms and watching bodies go flying out...and it sure was fun ^__^ Certain other games *cough cough Farcry* had made me dislike monster fighting in human games, luckily the monster fighting in Riddick is a blast and it really gave me the intense feeling that I hope Doom 3 will provide throughout.
In the end I really had a lot of fun in my final day of playing Riddick today. The length was just right and the immersive environment was well executed. While IMO it's not the kind of game that will end up in my top10 like say Ninja Gaiden, it was still a great experience that I'd recommend to others, and I look forward to Starbreeze's next game.