I only got to see this recently - at long last - on dvd. Truth be told I had never expected much from it, having seen just a couple of photo's from it where Cagney was posed somewhat ineffectively in Chaney not-really-as-good make up.
I had also heard that it took liberties with the truth - particularly with the very ending.
But, taking all that into account, and having now seen it, I can say that it is really worth a watch, flowing well as a drama. The recreations are better than the photos I had seen and it's got James Cagney in it. Legend.