It is a good game, If you are wanting a tactical first person shooter. This is not the game for you. It is a Run and Gun game. In Halo online multiplayer you can sometimes unload 20 shots into some one and not drop them. So it is def not a tactical shooter, takes some thought but not much.
But I play Halo Campaign for the story... it has a pretty good story and I enjoy it.
Just thought I would add this to what I said before.