Successful or not, I admire what they were trying to do in the movie version of the Wiz. The original conceit of the stage play was to bring an urban aesthetic to the Wizard of Oz story. In the movie they tried to bring it even further by setting it in contemporary NYC (1977 at the time) and by making Dorothy older and putting her in a time of life when she has to decide to cut the apron strings and finally become her own woman. I also liked the choices Sidney Lumet made when he filmed all the dance sequences. He used a lot of master shots and chose not to move the camera a lot. In this time of MTV quick cuts, it's refreshing to see dance on film in the context in which it was created. The choreography is huge and done by hard working dancers. You can actually see their work in this film, not just an elbow here, a close up ankle there, etc...
Also, we forget that film is a very different medium than theatre. It isn't enough to just go into a theatre and record the stage version. That's fine if you're going to make an archive. There have been some really good filmed versions of plays and musicals on PBS. But you still can't get the full impact of being there in the theatre with the live actors. Although I thought the broadcast of Piazza was very good, I didn't get the goosebumps that I did when I saw Vicki Clark do it live. So when producers make a film of a musical or a play, they always try to reconceive it so that it stands alone as a film in it's own right. It's what any good artist would do. Unfortunately, most of the time the movies fail. Plus it's hard to compete with any romantic notion one may have had of the stage version and not to let that go when watching the film version.
Mmm, Mmm, I feel sorry for the poor folk that got to pay to see this play. - The Maid from "Bullets Over Broadway."