I've just finished watching the programme and here are my rambling thoughts about it.
I enjoyed it and thought it was very well done in that assured, calm, analytic without being anaemic, BBC4 style.
It made me remember where I was when I heard that Kurt had died - I was with my dad at a scrappie's yard getting bits for a car when the news came over the radio. I don't remember what kind of car it was and I'm usually pretty particular about those kind of details so it definitely threw me off my game that day.
It made me feel angry that I felt like that much of an an outsider at the time that I considered Nirvana to be something the cool kids listened to - I didn't get into Nirvana until I left school in 1993 and even then I went In Utero, early stuff then Nevermind last.
It's given me an idea for a song.
Finally, it was a Gibson bass fest, which tickled me greatly. Krist is a giant - he makes that RD Artist (which I considered to be a big bass when I had one) look like a toy
TL:DR, I enjoyed it.