Byron Hinson at ActiveXbox has posted a Halo review, and he gives the game a 95% rating:

What can I say? Graphically Halo is miles ahead of any other console game released today. Sound wise again I have to say, I haven't really heard such a great range of voices, sound effects or Dolby 5.1 in any other game ever. Gameplay can become a little repetitive but in saying that, I enjoyed every moment playing Halo and if you play all of the different difficulty levels then you are going to be treated to different endings.

The only negative points in the review included some framerate slowdowns, level repetitiveness, and I want Halo 2. Which I suppose isn't really a criticism.