While the button pressing got annoying after a while it wasnt that big of an issue for me.
Also, all the Halo games are linear. They all have set paths that you have to follow through a "maze" in order to go through the game. I found this to be no more apparent than in any other Halo game.
Just keep in mind that its all personal opinion.
I wont call H4 the best campaign but it is not the worse one out there, at least for me.