We find the "broadway shows" to be ok. However, they really shouldn't (and apparently no longer) attempt to do much more serious shows. I thought the "Opera" show on VOF to be quite awful - with attempts to do highlights with extremely difficult arias from an assortment of operas in various styles that even the most accomplished singers won't even dare try to combine into one show.
I also haven't found the "serious" classical performers to be that good (was not on the "spotlight on music" cruises though).
I think they should concentrate on local musicians and otherwise work on the "lighter" entertainment selections.