Much better than Halo 4...
I've replayed the campaign in every Halo game at least once with the exception of Halo 4. I did finish it not long after it came out but I had to force myself to finish it.
I've tried replaying it several times over the years but it just seems that the developers thought several times throughout the game: "okay, this level is a little short, how can we make it longer. I know, let's have him get to this door but when he does he finds out that it's locked and to unlock it he has to go hit three panels."
All that said, I find myself re-watching this about once a year.