I first saw this film on a long flight, and found it intriguing. Then I bought a copy so I could show it to the other DrC. This done, it's time for a review, with spoilers.
Miss P is a fantasy film, I suppose, in the same sense that the Harry Potter films are. Start with several strange assumptions about "special" traits children might have that would cause them to be deemed "peculiar." A child who can start fires by touching something flammable with her hands, another who is lighter-than-air and must wear lead shoes to stay on the ground, kids who are preternaturally strong, or invisible, or so ugly as to cause convulsions in any viewer.
Now imagine that a group of adult peculiars who can shift "time" itself decide the safest life for peculiar kids is to not grow up but to live in the everlasting present of a perfect day, endlessly repeated. Whereas a group of peculiars who did mature have turned into bad hats who prey on the children.
Eva Green's Miss Peregrine is as quirky as Julie Andrews' Mary Poppins was, by turns stern and loving. The kids do a fine job, one hopes they won't have the disastrous adulthoods most child actors seem to grow into.
The trick with a film of this sort is to make you care about the kids, and about a budding romance between two of them, all in the midst of much strange and fantastic violence. Oddly enough, the film succeeds in doing just that. I think it fair to say we both enjoyed it, particularly on a second and third viewing. Enjoy.