What made the Halo 2 campaign so awful? I remember being annoyed at the end. of course, but the details of the campaign are mostly lost to time (haven't played it since).
Having played it numerous times, it falls apart after you leave Earth. I don't mind the Flood or the Arbiter. But the Arbiter's levels are so bad. Namely Quarantine, and Sacred Icon. Confusing mix mash of crap on a stick. Really I just challenge anyone to go and play those levels on at least Heroic right now and still defend them as being good.
I did like the the part of the Campaign from when MC lands on the 2nd Halo through the destruction of the temple. At least, I enjoyed doing my best to keep the original set of ODST alive as long as I could.
And my favorite map will never be re-made. Terminal, and it's killer train, was pure awesome. And giggle inducing as I'd abandon a tank on the tracks for the enemy to board. "All Aboard!"