I can vouche for 1337 Gamer and tell you all he has played and liked the other Halo games. I've played with him in both Halo Wars multiplayer (got my ass handed to me) as well as Halo 3 multi (kicked some ass :D). Anyways stop labeling people because their opinions differ from yours.
While I disagree with him, campaign has always been a massive part of Halo for me, I can understand why he doesn't like ODST seeing as he's mostly into multiplayer. For anyone that is into multiplayer for their games I do not recommend buying ODST unless you don't own Halo 3. If you enjoy a good campaign however and playing co-op then I highly recommend this game. Simple as that, stop the flaming.
The definitive evidence that video games turn people into mass murderers
