Two thoughts from me. First, if you've never read the book, then you might have a little trouble catching up as to what the heck is going on from the beginning, it takes a bit for pieces to fall into place to make sense of the timeline, and what's going on. That said, once it gets going towards the middle, it is enjoyable from that standpoint.
If you HAVE read the book, you're going to be a little irked at the changes and deviation from the book. As it's "based upon the book", obviously there will be liberties taken, and things changed for better or worse. I just felt after reading the book last night, and then watching it today, that it was more worse than better. It isn't to say it's horrible, but there's something to be said when there's a successful book or series and then the movies stray far enough that it turns off the people that went and watched it more than it excites them. I mean, characters are changed in their roles, other characters like Miss Peregrine herself being different from what the book portrays her as, as is the doctor (though they give it an explanation later in the movie to explain that appearance), a completely different approach in the showdown, and things like that. And most of these little things didn't need to be changed for the movie's sake, so it's peculiar as to why they did (see what I did there?).
If you've read the book, go into it knowing that it's similar, and you should still find some enjoyment, and maybe even more so than other people that don't know the backstory from the reading. If you haven't, try to keep up, and you'll need to pay attention to piece together the timeline of what happened and so on, but you should be fine to enjoy it too.
I'm not sure it was successful enough to warrant venturing towards the follow-up novels, which is kind of a shame, because the way the first book left off, I am looking forward to the next one, and it's one of those series that even with the tweaks in the film, I always would enjoy seeing it to the end. (Then again, I also thought they should take and make all the Dirk Pitt novels into movies too, because I enjoyed reading them all for what they were, and actually liked watching Sahara lol)