It's been a while since I read a book within the Wayward Children universe, so I was sufficiently confused jumping into Come Tumbling Down; there was no way around the amount of Googling I did to determine who was who and what happened previously. 

After getting reacquainted with the characters and their doors though, I fell into the story so easily - McGuire's writing as an unnatural ability to pull you in and has more depth in under 200 pages than most 500+ page books. 

While I think Jack and Jill's story didn't need another book, I felt like this was a nice way to round out their characters.