Jon and I finished Halo 3 on Monday night. Overall I enjoyed the game, though I felt that it was really short since Bungie spent most of their time working on the multi player.
Bungie, as usual, did a good job of keep up the frantic pace of 30 second battles every minute or so. This leads to a lot of high stress moments of getting owned by aliens with the final satisfaction of killing all of the bad guys.
On thing that I thought was interesting was how they gave the covenant a huge scarab tank, which could destroy just about everything and was quite a pain in the ass to kill. The first time we encountered it Jon and I got killed pretty quick and had to resort to one of us pounding it with a tank while the other one ran around waiting for it to fall so it could be killed from the inside.
The last time we encountered the big tanks the game was nice enough to give us aircraft to attack with. I flew Jon over the tanks and and he dropped off and blew the tanks up from the inside. It was quite fun.
I was disappointed in the last level as it was to much running and not enough gunning.