Martin, Walken and Peters deliver strong performances. I feel like Devin misdiagnosed Martin's performance as his smiling exuberance isn't snark but closer to Amy's vision of wanton striving. I didn't empathize with Martin until seeing him mouth the words to the musical - the performance shows an insane love of this Depression-era music.
However, Arthur is unquestionably despicable. He loves to the point of overwhelming the willpower of his female targets (notably the visually-impaired girl is not charmed by the"handsome" Martin). Arthur's aggressive masculinity is given comeuppance only through (as Devin harped on) an arbitrary murder that has unearned neat screenwriting.
Is the movie trying to punish Arthur? It fails at that since he is a victim of fate.
Is the movie trying to humanize Arthur? It does show the power of his passions yet he gives up on his wife and two careers for... sex?
I may be biased since I'm not wooed by the 30s or musicals, but the movie doesn't skewer either in a clear way. I disagree with Devin that it was constructed/directed sloppily as the blend of lip-sync and honest-to-goodness dancing is a fascinating blend of aspiration and unused ability. The theme is hard to discern outside of ruining Fred Astaire's memories.
The punishing unfairness of the Depression and the music industry comes through at times but is, IMO, overwhelmed by Martin's scumbaggery.
Storytelling: uneven and overwhelmed by the music
Performances: strong top-four but no set tone.
Influence: bummed out Steve Martin, liked by Pauline Kael and Amy, determinedly difficult to recommend
Overall: best send-up of half-century old music adapted from a British series.
Not that entertaining if you don't like the songs, cruel male characters or over-packed screenplays. You have to watch it closely and it doesn't really reward you for doing so. Better Steve Martin movies, better musicals, better critiques of Depression-era. Ambitious but not Canon