It's solidly fun. Other reviews say that it's more of a pop concert than a musical, which is true, but I don't really hold that against it; the show clearly knows that it's a pop concert and is doing that on purpose. In fact, I would say that's its primary selling point: it does make a quite good pop concert. I saw it in San Francisco and the performers were excellent.
Unfortunately, Six really, really wants to have something to say about historiography and feminism, but is too busy patting itself on the back for having had the thought "maybe we should tell the stories of women as more than side characters in the stories of men" to actually, you know, tell the stories of women as more than side characters in the stories of men. Furthermore, for all its claims to be feminist, it presents women as gossipy, infighting caricatures on little to no basis, and its treatment of serious topics is... lacking, to put it lightly. It's the shallowest imaginable version of a feminist message, yelling "queenspiration" and "herstory" while presenting the lives of real historical women as if they were either a competition or a girl power parable, and the show appears to sincerely think that historical revisionism amounts to empowerment.
I would be thrilled to watch a play about the life of Catherine of Aragon as a full and complete person who did more in her life than marry a man, or that looked seriously and head-on at the horror of the life of Katherine Howard— but this was not that play. And that would be okay, not everything needs to be a deep and serious portrayal of historical reality, I came here for a popcorn show and I'd be alright with getting one, if it weren't so self-congratulatory about its gutless feminism.
Overall I would say that the soundtrack is full of bops, it can be very fun if you aren't taking it very seriously, and if you want a vaguely Tudor-themed pop album, this is your place— but as a work Six desperately wishes it was Hamilton and it just doesn't have the thematic chops to pull that off. If you've heard the songs in isolation, you've gotten almost all of what there is to get: save your money and stay home.