It was completely different from her educational experience before that (not unstructured, but still... much more open-minded about education, and smart about guiding students to think about their place in the world) and the experience had a huge positive effect on her life; we are in touch (and in some cases, close friends) with a startling high percentage of her classmates there, and we've met up with (and often been hosted by) UWC classmates in Austria, Netherlands, India, Australia, France, Malaysia, and various parts of the US (and probably some other places I'm forgetting at the moment...). And despite being quite a diverse group, they're generally pretty interesting people to talk to.
I didn't even know such options existed when I was in HS; and probably would have thought it wasn't for me, at that age. But looking back now, I wish I'd gone as well.
Now we have small children, and they're obsessed with reading/writing, numbers, and creative play just like we were as kids -- so they're far ahead of their age group, generally -- but we've kept them out of school so far. We're trying to figure out a path for them through the available educational options, and we're strongly inclined towards more experimental approaches.