It really sucked me in... and all I can pretty much say is, this is the game halo 2 should have been. It took everything from the first game, went nuts with new weapons and vehicles, and refined all the gameplay. There were many a epic moment where I just found myself with my mouth wide open going, "Holy crap did I just do that?".
This was a breath of fresh air for the series, and I have a feeling I'll find myself like I did with the first game, playing through the campaign every once in a while, be it on co-op, or just for the sheer enjoyment of it.
Also, it was pretty damn hard :E. I was playing on normal, and was getting my ass kicked in a lot of spots. I can't imagine it by myself, on legendary...