What's so cool in "Homestuck"?

Homestuck is about like reading The Lord of the Rings in that the beginning is slow, and the character development early on is rather heavy, but also like Tolkien's work, once it picks up the pace, it rarely slows down. It's a huge clusterpineapple, sure, but it's a sort of controlled chaos where things that seem irrelevant become plot defining later on, and things that might seem important at the time are either less important than you'd think, or don't come into play until way, way later.
The other two things that give definition to Homestuck are the sheer amount of pop culture that's been amassed since the 1980s and 90s, and the music. Homestuck has around 15 albums and counting, and excluding some of the remixes, almost all of the songs have been used in the flash animations at some point.

It took me a while to get around to reading Homestuck, and I wasn't very keen since I was being badgered about reading it, but once I started and got about mid-way into Act 2, it's been really entertaining and fun.

And on the subject of the fanbase, those people scare me, plain and simple.