Mixed reactions, but most of them pretty positive.
Graphics 8.5/10: This isn't Halo 2.5. Its really Halo HD. Nuff said. just kidding. So yeah thats graphics but the game enviorment was much like Halo 1. I didn't like that b/c of the repetiveness.
gameplay 9/10: Glad Bungie stayed with the old controllers but with tweaks. Tweaks that make the game so much more comfortable.
Sound/music 8.5/10: Surprize surprize. Halo games always have awesome music. In halo 3 it felt like bungie had a feeling everyone was going to listen their own music or just play multiplayer 24/7.
Value/replay value 9/10: You get what you buy. You have all the extra features such as forge and uhhh that feature were u replay your gameplay.
Overall: 9/10 I feel really "meh" about Halo 3 and honestly i liked Halo 2's storyline and campaign a lot better. But in muliplayer Halo 3 owns and the campaign comes close to halo 2. Its worth getting, i guess if you enjoyed halo 2.