Floyd are an interesting band in that they have quality bookended by less good (to me) albums. Meddle, Dark Side, Wish You Were Here and Animals are terrific, but the early stuff I don't like, although I obviously have sympathy for Syd. The later albums are a bit meh for me too. A bit too much Waters and not enough Gilmour on The Wall and Final Cut. The post Waters albums are good though not as great as their mid 70's peak.
From what I've read, Syd was wrecked by psychedelics and ceased to function as a normal person, very sad tale. It's hard to pinpoint where mental illness and drug abuse overlap, but clearly the guy just didn't know when to stop. It must have been a very strange time, the late 60's. The psychedelic gold rush claimed a lot of casualties.