Dean Takahashi at the San Jose Mercury News thinks Halo 3 deserves the hype it got:

But "Halo 3" and the entire trilogy deliver what few games do. It combines artistic peaks - in graphics, game play, music, sound, witty dialogue and epic story - into a cohesive whole that makes you feel like you're in a struggle to save the world. Just about every scene is fun.

On an odd note, that's one of the few reviews that used the word 'fun'.