As we’ve both mentioned and appreciated, these cartoons almost always have a lot of happy visual, setting-related business going on. It’s often excessive, or at least super-abundant; one imagines background and supporting artists really busily filling things in, and they do it very capably/attractively. The whole thing, put together, recalls the rococo. That means that it’s too much, but it’s a too much that makes sense in all kinds of ways. (Caves of wonders, shining eyes, giving kids all that you possibly can.)
Beyond that, or on the other hand, this is another entry in the Silly Symphonies series that makes me at least faintly grumpy. (Great) backgrounds aside, I have always found its foregrounds to be fairly unattractive. Romeo and Juliet and all, but the classical/jazz binary is too pat, and despite a few happy moments, the reconciling romance is pretty smarmy. There are some good battle bits, and I guess the fact that they almost kill their children because of their conflict registers in important and helpful ways. But maybe like a sort of similar war in the Fleischers’ Gulliver’s Travels, it never registers deeply, as in the original, as in the real world.
Music Land is definitely a rich curio, and there’s lots of substance to draw out of it. Maybe not quite as much substance actually in it.