This begins and ends with suicide (so, please put your controversial conspiracy theories aside [even if some do have weight]). I've seen this framing device before in The Hours, as it begins and ends with Virginia Woolf stepping into the River Ouse.
The graphic novel is framed as Kurt telling his life story after his death - from his childhood, teenage years, the meteoric rise of Nirvana, his relationship with Courtney Love, the birth of Frances and his death. It's a quasi-fictional account of his life, as we will never know all the real details that transpired - we only have interviews, his journals and the accounts of others to go by.
I think this is an interesting book - it never would have occurred to be to create a comic about Kurt Cobain, but it does work. I think the artwork is great - a lot of emotion is conveyed in the art and it does a great job of enhancing the story, rather than being pretty pictures that contain thought or word bubbles. I like that it uses surrealism in some panels to convey complex emotions, ecstasy of a drug high, or Kurt's own distorted, fantastical view of the world. Again, this is Kurt's life as illustrated and told by someone else - I believe the authors and artist had great respect for Kurt, but again, I would not take this as 100% truth, but you can tell extensive research had been done.
I think my main problem with this book is the framing device. I think it works in The Hours - Woolf's decent into the river with pockets full of stones is extremely powerful imagery, but it does not loom heavily over the entirety of the book; it doesn't detract from the other scenes with Virginia (all the sections with Virginia are the best part of The Hours, honestly). In Godspeed, while the act of the suicide is not drawn (it's the now (in)famous picture of his foot through the open door of the room above the garage), it still creates a heavy fog over the entirety of the book. And this may have been the point - the Greek tragedy of the rock star.
I would recommend this to Nirvana fans - I do think the subject matter is treated respectfully, and the artwork is great.
Maybe a part of me was wishing it would end with Kurt on a tropical island with the other members of Club 27, chilling with Amy and Janis, like in that Heineken commercial. Maybe Jeff Buckley's there too, even if he wasn't 27 when he unfortunately drowned (please listen to Jeff Buckley). I think he would be happy there.
Oh well, whatever, Nevermind.