I have to start by saying that I come to this discussion by having a distinct prejudice for liking stage productions of musicals more than their film versions. In a general way, stage productions are tighter, the orchestrations are more exciting than the lush, overblown film orchestrations, and most importantly for me, the suspension of disbelief is so much more effective with the stage production than it can be with the "real" film version. Now to specifics:
I am the only person on this Board and maybe in the whole wide world that has never seen the film of THE SOUND OF MUSIC, so I obviously cannot compare. I went to the Lunt Fontanne to see Mary Martin in THE SOUND OF MUSIC in 1960 expecting little, some of which was due to my anger in its winning best musical Tony and best actress in a musical over GYPSY and Ethel Merman. But I have to say that I thoroughly enjoyed the Rodgers & Hammerstein musical. It is a very well constructed show, with the mountains being referred to, but not appearing as any painted set. Most of the music is good, especially the two songs for second (excellent) leads Kurt Kazner and Marion Marlowe. The actors were all very good, of course Mary Martin but also Theodore Bikel whose singing of "Edelweiss" ( Hammstein's final lyric writing ever), accompanying himself by playing guitar, was exquisite. True, there are the two sugary songs,"Doe, a Deer..." and "My Favorite Things" that I could do without, but the rest of the score holds up well. The excellent Patricia Neway as the Mother Superior sings the anthem "Climb Every Mountain" with great authority.
I loved the stage production of OLIVER which I saw in its Broadway debut with a very good Clive Revill as Fagin and Georgia Brown as Nancy. This production boasted the innovative unit set on a large turntable which allowed for fast scene changes and actual chases through the London streets. Englishman Sean Kenny was the brilliant set designer. There has been much talk of the film version on this Board and its superiority over the stage version. I liked it when I saw it in a movie theater back in the 1960's, but felt its large ensemble numbers were typically overblown. However, I shall have to buy the DVD and take a closer look since so many here have pointed out the film's virtues.
I was fortunate in seeing the entire original cast of MY FAIR LADY in 1957, at the ornate Mark Hellinger. As a Broadway show it works perfectly. The film is good, but it moves slowly for me, unlike the tighter stage musical. And, frankly I have a problem with actors being dubbed in films--there is something dishonest about it. It was a joy to hear a very young Julie Andrews singing on stage, although I have not enjoyed her film work.
As for WEST SIDE STORY, I was fortunate to see the original Broadway cast (minus an ailing Carol Lawrence) at the Winter Garden in 1958 and also saw it after it toured when it returned to the Broadway Theatre on 1960 ( also minus an ailing Carol Lawrence!) I agree with Eric Montreal that it is easier to suspend disbelief seeing the electric dancing on stage than it is on film on the actual streets of NYC. Also, being able to see the charismatic Chita Rivera singing and dancing "America" was a privilege. She will always be Anita to me. But the biggest single failure of the film for me was the casting of Tony. Richard Beymer comes across as effeminate in contrast to the solid Larry Kert on stage. Kert's singing is also superior to Beymer's singing (whether it is Beymer's actual voice or a dubbed voice is immaterial to me). And I liked and appreciated the "Somewhere" ballet in the stage version.
I am trying to think of a movie musical that for me was superior to the stage version and can think of none. But just to show that I am not against movie musicals totally I would like to mention SINGING IN THE RAIN which I never tire of watching, and THE BAND WAGON which is very funny and tuneful, based loosely on the stage revue from the 1930's. And, as I said, I will take another look at OLIVER.
I cannot end this post without mentioning the 1962 film version of GYPSY, which despite the always charming Natalie Wood and stage holdovers from the OBC dancer Paul Wallace and the stripper with the trumpet Faith Dane, is so awful especially Rosalind Russell and Karl Maldin. I will not allow this film in my house--it is sacrilege.
"Madam Rose...and her daughter...Gypsy!"