I'm a fan (and you should be too) because...The Avett Brothers music to me is a representation of what happens when people grow up together - as a musical family. The breadth of style combined with original lyrics and obvious skill on a variety of instruments as well as wonderful vocal harmonies is just spectacular.
I have yet to be among the concert attendees but hope to remedy that gap in my Avett experience this summer (several times if all goes well!). I do however own all their songs, purchased legally, not just downloaded.
Another great thing about the Avetts is that the students I work with are totally hooked on their music...our school, The Toledo School For The Arts, seeks to expose students 6-12 to the old, and new and the Avetts music allows us to do this on many musical fronts.