Jay Cheel’s review published on Letterboxd:
Outside of a few missing voices -- Dave Grohl in particular, not that I really felt the need to hear from him -- Montage of Heck is a pretty complete package. Brett Morgen seems more interested in telling the story of a person rather than the story of a band, and that's fine by me.
I thought I'd have an issue with the animation in the film, but it was very well executed and resulted in one of my favourite sequences (the 4-track songwriting montage). It's amazing how much of this story is told through notebooks and journals, and the additional animation certainly helped sell that narrative tactic (which reminded me of the animated sketches in The Devil and Daniel Johnston).
Also, all of the footage of Kurt and Courtney was appropriately gross and unsettling. Oh, and where the film ends is perfect.
It's pretty amazing watching such an accomplished (Is that the right word? Celebrated? I'm not sure.) life flash before you in just over two hours only to come to an abrupt end. Certainly makes you realize how fleeting everything is.