I have a weird relationship with AtS season 4. The thing is a mess, and I loathe everything about Cordelia and her evil octopus baby that turns into a beautiful full grown black woman*. But I LOVE the Beast. He isn't a terribly deep character, but that SOB was the coolest looking demon from either show. I think having him speak was a mistake, but even when he did, his voice was deep and intimidating as well. Faith was amazing, Willow's guest appearance was better than her entire storyline in season 7, and once I got passed how batshit crazy Jasmine's introduction was, she was kind of a cool and different threat with an interesting motivation.
Angelus is in the middle. He was hilarious and creepy some moments, others I wanted him to just shut the hell up. It's like DB drank a ton of caffeine and they just filmed him shouting random stuff that came into his head.
Does BtVS season 5 get a bad reputation? It's probably my favorite, but it seems to be middle of the road. Some love it, some hate it. A lot of the elements I hate in season 6/7 started to creep in here, but the positives far outweigh the negatives. Despite the Knights of Byzantium and everything Spike related outside of "Fool For Love," there's not much here I don't like. Even Glory is pretty great once you compare her to the Big Bads surrounding her (Adam, the Trio and the First. Yeah, I'm going with the Big G on that one).
*If we had to have evil pregnant Cordelia at all, they should have gone all out on the birthing sequence. What, they suddenly chickened out on how ridiculous it could have been? Imagine something similar to the medpod scene in Prometheus.