I went to a friends house everyday this week to play it, and I must say, it was fuckin' beautiful. The graphics are amazing. I especially love the look of the cannon on the Wraith.
Anyway, campaign was definitely fun. We beat it on normal mode in probably ~10 hours. The ending was lame and left it completely open for a Halo 3.
The multiplayer is of course bitchin'. The one thing I hate about it though is that they nerfed punching with weapons. It takes the same amount of hits from any angle. Punching is only useful if you take their shields out, so it's good with the plasma pistol fully charged. The beam sword is rigged. You can lunge in any direction so long as you're close enough, this includes up onto the edge 20 feet in the air so long as your reticle was red.