Miss Peregrine's Home for Peculiar Children is a book built around a gimmick. Yes, old photographs are creepy and unsettling. It wasn't a bad idea to use them in the book, but the problem is that they feel forced at times - the protagonist will literally happen upon a photograph, describe it in great detail, and then show it to us. There is often very little relevance to the plot.
And what about the plot? It starts out interesting, with the suspicious death of the main character's grandfather. He ends up traveling to Wales in search of answers about his grandfather's mysterious past. When he gets those answers it's a bit anti-climactic, and the book turns into a standard sort of boarding school adventure. Comparisons to x-men are completely justified. Then the book tries to explain its mythology, and it just doesn't make very much sense. The main character is a drip who has no personality that I could find. His parents are terrible caricatures of bad parenting. The peculiar children were promising, but it was a lost opportunity. Spoiler: If the children are really eighty years old, I would have expected them to act like it. That would have been interesting. Instead we are treated to a creepy romance between the main character and his deceased grandpa's teenaged girlfriend.
In short, a lot of promise, but it didn't amount to much. It will probably make a good movie (I assume there is to be one, as it seems every YA novel these days is sold before being published!)