I just beat it last night on normal and it took around 7-8 hours. The graffix were improved from the beta a lot and really look good in the wide open enviroments. The flying parts are freaking cool and make up for some of the levels that drag on a bit to long. I loved how you fight those scaab things a lot in Halo 3....that was one of the best things about Halo 2. Plus the last escape ride was incredible and made me wish that the other levels were explosive like it. Of course the multiplayer is awesome as usual so its still going to be the biggest game ever
Now to the bad parts.....the story was a HUGE bummer for me. I'm not going to get into specifics, but I will never play the single player again. It was torture playing though the numerous flood levels AGAIN and not even close to being fun like the regular brute levels. My biggest gripe with the game is the AI of your teammates and the enemy. Countless times I killed enemies that had gotten stuck on a piece of the enviroment easily or my teammates were rendered useless because of the same problem. Maybe I should have played it on Heroic, but I didn't have that problem in the first two on Normal. Also, thoughout the game you get these "Bioshock" type flashbacks in your head that become very annoying and don't really do much to advance the story. I kinda wish I played this before Bioshock, because it kinda made me more critital of these things, but its still a good game. Just keep a open mind with the rough levels and you will be rewarded with awesome vehicle levels!