I played it. I found nothing amazing about it but I found nothing terrible about it either. It was an improved version of Halo2. How much improved is hard for me to judge since I havent played Halo2 in a while but it felt the same to me. Nice smooth gameplay. Good sound, good graphics.
The graphics were not amazing but not bad, in fact they were not distracting in anyway. I didnt look at them and go "wow amazing" but I didnt look at them and go "this is crp", it was just..... Halo. Halo is halo, its got its own graphics style. Not too realistic, not too cartoony just Haloy. It was fine, I could see everything, no popins or magic fade outs.
Gameplay was solid, menus were solid. It was halo. If you loved halo2 online you will probably love halo3 online as it is an upgraded version of the same game.
What could set Halo3 above the other halos is the single player and we will have to wait to see if that is amazing and awe-inspiring or if it is just....halo, which would be fine too (just means it will be a solid game and not an amazing game, not every game can be amazing).