This review may contain spoilers. I can handle the truth.
On the one hand, the 'magic of cinema' montage at the end was cringe as hell and reverse engineering a bunch of references to Singin' in the Rain seems like weak historical fiction writing... but on the other hand Chazelle does capture the way watching Gene Kelly perform singin' in the rain feels like seeing the face of god, the stargate from 2001, the infinity of cinema.
Edit: watch Inserts (1975) instead