I remember hearing Kansas on the FM AOR radio, mostly WMMR and WYSP in the mid-seventies, and thinking they were okay. I wouldn't change the station if they were on, basically, but I didn't really appreciate their music or their artistry until I heard them played in a neighbor's basement that had a killer stereo system. That brought Kansas to life for me.
I also remember a trip to the Ocean City boardwalk and a busker who refused to play "Dust in the Wind" because it was 'the hardest song ever to play properly,' and he 'didn't want his fingers to bleed.' He got booed by both those who requested it and wanted to hear it. True or not, it gave me added awe for the tune.
My favorite Kansas song was "People of the South Wind" from the album Monolith, a song and an album both considered failures, but its content pulled at me. Native Americans shoved aside by the white man, and wearing space helmets on the cover of the album drew me just like the fantastical elements of the cover of Point of Know Return. It's still one of my favorite songs from that time.
The doc is compelling, and tells stories of their early days, composition of songs, dealing with Don Kirshner, fighting with Steven Tyler, and the internal struggles of the band. This is one of the better rock docs I've seen, cool for Kansas fans old, new, or fans not at all. Check it out.