Absolutely worth seeing (even if I shut my eyes in a couple of places). Remarkable imagination. Glad to have seen it.
A fairy tale, but definitely not one for children. The world of wartime Spain and the world of Ofelia's quest are both dangerous worlds, as so many of the worlds of unsanitised fairy tales are.
You get accustomed to knowing, without even thinking about it, the story arcs used in Australian or American or Canadian or British films, and then you see something like this, which ranges into territory you can't predict. So you live in the film's time, moment by moment, caught in your seat by engagement, terror, wonder.
Image source is the English language website of the film, which has a bunch of freebies including the English translation of the screenplay as a .pdf.