The only thing keeping me from returning this pile of crap is my love for the original game (and the hopes that I will someday play the original campaign in 3d once I get the hardware). Otherwise it was a complete disappointment.
As far as the campaign goes, it was nothing different from the numerous halo mods I've seen back in the day. It actually somehow looks worse, like changing space to blue, the new character models, etc. But people will disagree with me on that. Otherwise, I have no real gripes with the campaign other than the fact that they were to lazy to go into the code for more than 2 player co-op (which would've been difficult but worth it). Other than the 3d option, I'd rather stick to the original.
The multiplayer is just pathetic. Ask any old MLG/competition buff and they will tell you that the original game had the most balanced, and simple yet complex multiplayer. When I heard it was going to be on the reach engine instead of just a port of halo pc, I was disappointed but still had hope. Then when I got the finished product, my heart was broken. Playing it just made me pissed at what a mockery of the first game it was. They didn't even attempt to simply change the values on guns for damage, accuracy, speed, number of bullets etc. They're literally the same as reach. Not to mention the little things like plasma no longer stunning the target, or lack of ladders, or the battle rifle on a halo 1 map. They didn't even include all of the original maps, including classics like boarding action or chill out (I may be mistaken about the last one because I only played about five matches). MLG's former flagship competitive title has been relegated to a piss-poor map pack that should've been in reach in the first place. The hopes for best game from my childhood finally coming to xbox live are finally extinguished, after waiting for ten long years...