Ah, this is a good game. There are always going to be biased reviews, and I will try to keep this as unbiased as possible.
First, I love the graphics, the multiplayer, and the campaign when played with a couple friends was pretty fun. Although the story was really weak, fortunately, Halo is more about multiplayer. And the Multiplayer is great! It's up there with Battlefield 1942, and Battlefield 2's multiplayer. (Although glitchy, it's insanely fun...) Anyways, this game is the best of the Halo games I would say, and it deserves a B I would say. I think the only games that really deserve anywhere in the A range, are extremely innovative games, such as BioShock, Metroid Prime, and Little Big Planet. Or RPG's such as Zelda, or Final Fantasy. But as far this shooter goes, it deserves a B cause the fragging is insane fun. No doubt about it.
My only problem with the halo games, is there is almost no tactical aspect, some people will argue, but these games are run n' gun games. And this is both a good and a bad thing. You take Counter Strike for instance. Unless you were playing on CEVO, CAL, CPL, or other major competitions, strategy didn't matter nearly as much as being a good shot did.
Now, you take a games like the ones in the Battlefield series. Mainly Battlefield 2, and Battlefield 2142. They are much more tactical, and the best players play with strategy.
Halo 3 with it's new weapons (ie: Bubble Shield) Has added some more tact to the mix, and it has put it somewhere between Counter Strike and Battlefield. This is a good thing, cause at times Battlefield feels too strategy oriented. And Counter Strike almost always feels too run n' gun.
I respect Bungie for one heck of a game, and those shiny graphics make my eyes hurt if I play for too long :p
Anyway, this game earns a B from me =)