Actually, the worst thing about this book is that it's going to be a series. I'd say quit while you're ahead.
Reason being, this sweet little young adult novel does not need a follow-up. It contains itself nicely, and has a nearly-perfect ending, bringing all the story elements together into one thoughtful scene. The only thing I can think the author intends with another set of volumes is turning it into a creepier sci-fi thriller type of series - still for young adults (or whatever we are calling them these days), but not a romance.
Because the "reverend" is the only unresolved character among them all by the time you finish the volume. "A" inhabits one body per day, always moving on to another body, hoping not to impair or even affect the person during that day. Since "A" comes into contact with a variety of people, the book explores gender and personalities more than anything else, giving extra weight to being thoughtful, caring, loving - the usual themes of this kind of teen book.
You wouldn't want the next book to push the same themes, so I can only expect that it's going to try to mess with "A"'s usual rhythm. I think I'll wait and see what the critics think first.