A very good beginning to a phenomenal series!
Multiplayer-wise, it does kinda suck that it doesn't have Xbox live, but then again, if it did their would probably a butt-load of ways to glitch and cheat seeing as how so many people did even in Halo 2 (which is noobish!). One thing that is different in Halo 1 in general, that a lot of people seemed to like was that health wasn't a regenrationable shield, you had to find/acquire health packs to heal, which makes staying alive MUCH more difficult obviously. The guns are beyond extra powerful, including the shotgun (which seems to be a shotty snipe by itself), grenades and rockets seem like they could blow up a city square, and the pistol can be used to snipe quite accurately and quickly also. Although the weapon damage is quite messed up, it makes for a very fun and entertaining game with friends.
A very good beginning to a phenomenal series!