I saw the show last night and loved it, and I really don't think there's anything to worry about. I understand that a few tweaks have been made, and there's certainly nothing in it now which I can imagine anyone finding inappropriate. Alternative and unconventional, yes, but that's what I would hope for from a Junction treatment of a fairy tale.
To give more detail (spoiler alert!), it's clear that Rapunzel is generally wild and hairy besides just having long hair on her head, and that the tower is full of hair, but there are no references to her pubic hair specifically. There are a couple of mentions of bikini waxes in the songs set in a beauty parlour in town, which are about a culture of excessive conformity, but as part of the general list of stuff people are pressured to have done. I imagine that would go over the heads of many children; if they know what it means already then I really don't think it's going to raise any issues. Rapunzel is really celebrated as a heroine precisely because she doesn't fit the mould, and all this opens up questions about different kinds of freedom, including peer pressure. So it's definitely fair to say it's a forward thinking and body hair positive production (!), but not in way which I think will upset anyone who has signed up to go to a show with a Junction twist on a classic.
So that deals with the pubes question! As for age appropriacy generally, I don't think I'll take my four year old as he doesn't know the story of Rapunzel and I think he might not last through the whole thing. I think age 6 or 7 up will get the most out of it in terms of following the story, but that's not to say littler ones won't have lots of fun too, that was certainly true of some younger ones I was near last night. The start does bring out just how creepy the fairy tale really is, but the second half has more rousing opportunities to boo the fabulous villain and root for Rapunzel. The kids in the audience were getting right into it. The performers are all really fabulous.
(NB I am not working for the Junction! But I would echo the suggestion of contacting them directly.)