I don't want to start a dumpster fire here, but precisely what is "wrong" with The Sound of Music?
I am fully aware that HE Bishop Williamson doesn't care for it, and that is his prerogative, we all like what we like, and don't like what we don't like. I find Michael Buble's music insanely annoying. But that's just me. Some people love his music, and that's just them. De gustibus non est disputandum.
Aside from that, though, the only thing I could possibly find disagreeable about the movie, is that Maria was deemed by her Mother Superior to be a poor fit for religious life (and, by implication, if Maria had possessed a different personality, she would not have been a poor fit). That's the Mother Superior's prerogative. Being cheerful and ebullient is no sin. Maria went, she offered herself, but she just didn't pack the gear. Happens all the time. How many vocations might be saved if every young person who detects such a prompting, went to seminary/monastery/convent for a time, and gave it a try? How many vocations are lost because young people don't do this? (Affections for a member of the opposite gender, and egging on these affections, can kill a vocation --- this modern business of "date while you're discerning" is a vocation-destroyer if ever there were such a thing.)
But I digress. Back to the original question --- "why should we dislike The Sound of Music"?