I owe the PORGY AND BESS movie a lot. Taken to see it at age ten, when it was new, it was the thing that set me on course for a lifelong love of Gershwin. Not long after that I was pecking out the Rhapsody and Concerto in F (which I initially liked because the bluesy second movement made me think of moments in P&B) on the piano.
I've seen it at special showings a few times over the years. The main thing I would warn anyone about before seeing it their first time is that it's very "stagey", as opposed to a "cinematic" depiction of the piece. Last time I saw it there were times I wanted to scream at Preminger to get in there for a tight dramatic close shot. Or...something.