2nd book is definitely my favourite. Fast and clever in the way it unfolds Jake’s story, and the next two continue it well.
The books are about joining worlds though. He pulls in Wizard of Oz references and the like and that works but book 5 somehow fails to match this and references Harry Potter and Salem’s Lot.
What happens is the real NYC world is our world and because King is the writer they come through to see him. IIRC it’s all about them forcing him to finish the book for them.
I’m probably alone in finding his inclusion also quite interesting I’m a sort of weird way.