I remember seeing it on TV in the early 1970's (before it was withdrawn) and understand why it got such a negative reception.
For those who haven't seen it it is not a film of the full opera, but seems more based on the 1940's Broadway version which replaced much of the recitative with spoken dialog. I don't recall the acting being all that exceptional either.
What it does have (and it is preserved on the movie cast album) are those lush orchestrations conducted by Andre Previn. The album was released on CD in by Sony in the U.K. in 1994, but has long since been deleted.
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com