I'm going to assume that you know that your granddaughters like or at least don't mind insects.
But just in case you don't know how they feel about insects, I'd like to mention that this experience is not for anyone who dislikes, is afraid of, or is horrified/disgusted by insects. Yes, they're animated, and they're supposed to be cute . . . but . . . I didn't find it cute at all and there are sensations as well. Sensations I was not amused by. I was hardly alone in my reaction to ITtBaB.
If you're not sitting right near the exit, it's impossible to leave the theater. Ask me how I know.