I actually disliked the art trailer music initially, I love it now.The more I listen to the music samples from Halo 4, the more I like them. Some of it is sort of generic "action-adventure movie" stuff, but keep in mind, there is a lot of game to fill and not all of it is going to involve exploring mysterious alien structures. I'm sure Neil is operating under the mandate of "more and different" so that 343 has plenty of music to blend into the game.
It will be interesting to see if there is a bump in Massive Attack's back catalog when the OST releases.