I tried my best to avoid spoilers for this game. I watched all the videos from Bungie, E3 etc, and with baited breath I put the disc into the XBox. Presentation hit me, it is smooth. Obviously I will be seeing the intro to this game a lot - so I am glad it is cool. The single player game is pretty much like the single player of Halo - very good action, but again seems a bit too scripted. You can tell when you are about to have a major fight, and can tell when you have finished one. The skill levels have been tweaked. Try playing on Legendary now, and the covenant could hit you with a sniper rifle from the moon - they don't miss! Halo2 comes into it's own with the multiplayer options. It has been well thought out, and all the settings can be changed to suit the mood. On Live all Optimatch games are logged by Bungie, and can be analysed online to see just where that guy was sniping from!
I give this game a 10 out of 10 based purely on the multiplayer side. The one player side is very good, but you wont keep coming back for that.