S1 is kind of slow...mostly just mystery of the weeks. S2 builds and S3 with the Connor/Wes drama is amazing. S4 is the most epic season imo and is one of the best Buffy/Angel seasons ever. S5 is good, better than 5 but not as strong as the 3 seasons before.

And yes, S7 is probably the worst Buffy/Angel season EVER. Everyone is so out of character, the episodes are boring as heck (there was like five where they didn't even leave the house), it was cheap looking, Spike was supposed to be the "hero" image and there was just a feeling of apathy to it.