Right from gate, I quoted the word "game" for a reason. By this I mean the game as a whole: multiplayer, gameplay mechanics, after release content, continued support, community involvement, overall story, individual missions (story) and (enjoyment).
I define this because I still think that Halo Reach had better customization options, and the induvial story of ODST was riveting. Not to mention many people claim Halo 2 wins in the Multiplayer department. But as a whole, Halo 3 is a better complete package.
With that out of the way, what is left to say. I bought Halo 3 on a midnight release standing outside my local mall in the cold of NJ by myself. SO my opinion is clearly slanted. Trying to be neutral though, I still can not think of a bad thing to say about the game.
After all this time (20+ years) playing games, glitches and bugs are always expected in a game, no mater what; and Bungie was at the top of their game when they made this game.
This was also at the peek of Xbox 360's life, and Microsoft was riding on a cloud with console sales. There was no better time to be a fan boy.