Why?
It's probably the most consistently perfect jazz record from start to finish ever. Dolphy's bass clarinet sounds like no other instrument. It doesn't even sound like a bass clarinet. So deep and slippery and smooth. His improvising is fierce enough for free jazz fans, but melodic enough for my mom to enjoy.
Just get it. I've never met anyone who doesn't like it.
It's so good I even named my interweb persona after its opening track.