Uh, the "whole Xindi storyline" was one of the best seasons of Star Trek, period.
It was a terrible excuse for a storyline. They dropped all their exploration (which is what the series was about, humans exploring the stars for the first time), and went off to blow up a bunch of aliens bent on destroying the earth, because another bunch of aliens told them it was the right thing to do. Rubbish.
They modified it but it was still not great. Except for "In a Mirror Darkly" Parts 1 and 2. In those the completely changed it and it was HILARIOUS. I just fast forwarded it part the into song..except in the case of Mirror Darkly of course