Went to see Mary Poppins in London which wasn’t as good as The Producers, think it was definitely more a children’s thing, although it had some uplifting messages (Anything can happen if you let it!), and I think you needed to be much closer to the stage, as the actors were very stiff, and stayed in corners of the stage, rather than the centre, and everything seemed to be more facial rather than a big song and dance number- which seemed a bit silly. Whereas The Producers used the stage really well, so that everyone could see what was going on. Mary Poppins did have an amazing set though- it seemed to overshadow the actors though- think that was their main problem. And the dance numbers just weren’t big enough.
Think it would be a magical experience for little kids though, especially if it was their first musical.