Wife and I watched it tonight. I loved it, wife thought it was pretty good. It was quirky and weird. I really enjoyed the music. I was reminded of The Doors, Octopus Project, Joy Division, Laurie Anderson, Sonic Youth, Stereolab, etc. Apparently the actors played all the music live so that is pretty cool.
IMO, it deals superficially with mental illness but is more about expression of self, how we hide ourselves, and how the people around you can push you in a good or bad direction of life, and that the perception of that direction is different depending on the audience. There is also a a commentary on social media. It was funny but not ha ha funny in the American sense. All together I really liked it and would watch again.
Not sure if any of that makes sense, I've had a few drinks. I love you all.
edit: Frank's voice and vocal mannerisms reminded me of Johnny Depp as Dr. Gonzo/Thompson in Fear and Loathing. turns out the part was written with Depp in mind.