I've found Halo to be thoroughly mediocre.
It's a shame, too, because I definitely do think there's potential. It could be a great series, but instead squanders all of that potential.
I've heard good things about this one, with even the guys over at Penny Arcade saying that the new developer made the game better than Bungie could have managed, so that's something. I might give this a shot, but we'll see how that goes.