Library of Souls concludes the story of Miss Peregrine's Peculiar Children and wraps up the adventure.
I have enjoyed the series although I feel that the series went from being a very original and moving story into something more along the realm of a fantasy/thriller. My favorite is still the first volume. It was so original, the pictures were so bizarre, and I felt that it explored Jacob's reeling uncertainty and vulnerability at being wrenched out of his world and thrust into a dangerous and unfamiliar alternative world.
He is devastated by the separation from his parents and family and this loss tugs at him as he attempts to fulfill what appears to be his role in an epic struggle against evil. By the end of Library of Souls, he is superhero of sorts and his parents are reduced to clueless muggles.
That being said. I still really enjoyed the finale. The characters are lots of fun, the villains are dastardly, and Mr. Riggs' world building skills are as good as any other fantasy author that I can think of. You may like it better or less than the prior installments, as is your taste, but if you liked the series, you won't be disappointed by the finale.