A better ending, in my opinion, would have been to have Angel and his team destroy the Circle Of The Black Thorn, then let it end there. Sure, the Senior Partners are gonna be P O'ed at Angel, and they are most certainly going to retaliate , but that is for the future, and there will be time to prepare for it, just like there was time after "Chosen" for Buffy and her friends to regroup, organize, and prepare for the next inevitable apocalypse.
"Not Fade Away," in my opinion, should have ended either before the scene in the alley or after the battle was over. The way that Joss did it was, to me, like reading a murder mystery with the final chapter removed, or having to leave a baseball game after only the 8th inning.
Apparently I'm one of the few people who feel cheated and betrayed by this sort of thing, and I'm glad that so many people liked it that way. I just don't happen to be one of them.