Evan C’s review published on Letterboxd:
Yes, it's every bit as good as you've heard. Driver is magnificently unlikable, and his brooding demeanor perfectly captures Henry's dangerous side. Even from the opening number as the actors transform into their characters, Driver's expressions hint at the type of character he is going to play. The same can be said of Cotillard, who is sublime as his better half and shines like a ray of grace throughout the film.
This is a spiritual and thematic successor to Demy, notably asking the question what if the whirlwind romance of The Umbrellas of Cherbourg worked out, and what if that pushed the characters just ever so much further. It's a disturbing nightmare about the glamour of fame, in some ways Lynchian, in some ways still reveling in the magnificence of what is seen before us.
Carax is more than up to walking that line with perfect balance, and the score by Sparks aids him tremendously as it both develops the plot and comments on the function of the music simultaneously. For a musical about performers, the performance extends beyond the actors as well.
The opening voice over forbids breathing throughout the show, and while it's meant as a dark joke foreshadowing Henry's (Driver) offensive standup routine, it also is a fitting descriptor of the film, through which I sat enraptured for over two hours. And then, after a final scene which will hands down be my favorite scene of any film this year, it's time to stop watching and for the performances to end.