First things first: Paul Simon is a brilliant songwriter, but a lousy actor. He was absolutely dreadful in "Annie Hall," but at least that was a brief performance, clearly done as a lark for Woody Allen.
I'm not sure what, exactly, this movie was supposed to be. Was it a straight drama? A satire on the music business? A conjecture as to what Simon's career would have been like had "Sounds of Silence" been his only hit? All of they above? In any case, it's not a bad movie. Simon's scriptwriting is actually quite a bit more astute than his acting. But mostly, it's a formless vanity project, mostly a vehicle for Simon to show off his formidable guitar playing/songwriting skills...and, it must be said, his 40-year-old body (through plentiful shirtless and open-shirt scenes), which I have to admit is quite impressive, especially given his short stature.
Simon is actually quite sexy in this movie: the sad-sack, world-weary persona he affects (or maybe it's genuine) somehow really works for him. And I loved the inside joke of his character encountering a poster for "The Empire Strikes Back," aka the movie that Simon's then-girlfriend, Carrie Fisher, was starring in around the same time "One Trick Pony" was being filmed.
Blair Brown is perfectly decent as the Simon-equivalent's ex-wife, although Ms. Brown has subsequently said she dislikes the movie and doesn't wish to discuss it.