Curious to know what you guys think/like about Pink Floyd's early work

Listening through Pink Floyd's entire studio album discography these days. I mostly know their work from the 70's to 90's. I will admit, I haven't quite connected fully with their early psychedelic years from Piper to Ummagumma yet. I suppose I'm a bigger fan of their "BIG sound" that would evolve later on with David's important guitar riffs, solos, conceptual records, unique production and Waters' lyrics. Those first records honestly do not really delight me always. I'm really open to hearing thoughts, discussing factors and history of these records that could give me a more open perspective, and maybe understand the importance of these works. Why do some of you like them? Is it the history of the band forming? Starting out with Syd? Any documentaries or books that focus on the early years?