It's not a "kid play", but it's not inappropriate for kids, imho.
I started taking my son to operas and operettas when he was a toddler. (he's adhd, he has an *ungodly* attention span for things he's interested it). He's 9, now, and we've seen tons and tons of things (huzzah for local shows! Dress rehersal tickets are peanuts! Traveling shows are harder to arrange for good seat AND cheap tickets). Don't get M. wrong, we'd still see the 'full version' of travelling shows... but I J. can't afford to do it that often. I have the kid, though, who (used to) get ticked off about intermission in full shows. Don't stop! Don't stop! Now, of course, he like the cookies and cider.
I would let him see plays, operettas, and operas of a kind that I would in NO WAY let him see a similar movie. In no small part because the actors in a play come out for bows. Everyone lives. And theatre magic & special effects are radically different. A great thing about dress rehearsals, btw, (in addition to being able to leave) are the NOTES that are given. The director will stop between scenes for notes for the actors, so the magic is periodically bent, if not broken.