I think the RTS style is a great option for Halo! That was actually what the game was intended to be but that eventually fell aside to the FPS you know and love today.
However, I think it is sad and horrible that they didn't put in a Covenant campaign option. At least you get them for skirmish stuff! There are some good trailers, especially the gameplay preview which showed off some nice new units and some very cool small/large scale battles.
Side note, they did an awesome job recreating the Warthogs.
