Some will complain that the documentary doesn't focus enough on Nirvana, and there's a very good reason for that. It's not a documentary about Nirvana; the film is intended to provide a more intimate look at Kurt Cobain as a person and provide insight into his more private and guarded moments. In that respect it is pretty successful. Nirvana's history is very well publicised, and the film assumes it's viewers are already fans that know a lot about the band (Why else would you watch a movie about the band's frontman?)
The films biggest selling point is that for the first time a director had the full cooperation of Cobain's family and access to the archive of materials he left behind, much of it had never been seen by the public eye before. These include home movies dating back to him as baby, behind the scene footage, and audio recordings. There is also going to be a companion book dedicated to never before seen photos and other materials that were unearthed. Unfortunately, it's not as exciting as it sounds. There may have been information I had never heard before, but none of it was surprising or profound. It all falls in line with what you would expect if you knew anything about Kurt going in. (I'm sure some people will disagree and say they found it shocking, but I didn't.) That being said the archival materials were well utilized and had a good presentation that fit into the story that was being told. It was nice to see them even if it was an over- hyped aspect of the movie.
From a technical standpoint the film really is a marvel. The animated transitions were a great way to incorporate the drawings and doodles that littered Kurt's notebooks. There are also scenes featuring puppetry and stop motion that are also inspired by his art and/or song lyrics. These are all really cool and actually provide more insight to his artistic style and writing process than you would think.
Additionally, several segments are entirely animated, and they look beautiful. Doing this is much more captivating than just just showing people talk about events or have a voice-over with a slideshow of pictures. It was a very good choice, and adds a lot to the viewing experience.
The film's soundtrack features live Nirvana recordings, covers and remixes, as well as music by other artist that fit the scenes, such as the Buddy Holly song that plays over his parents home movies from the '60s. This is well executed and I particularly love the violin rendition of "Smell Like Teen Spirit" that was used to mimic an orchestral score in the longest animated sequence.
Overall the film is an energetic and seemingly honest look at Kurt Cobain and the man he was. It was well made, entertaining, and a worthwhile documentary that stands head and shoulders above any other documentaries about him.