The Stephanie Plum novels haven't changed all that much since "One for the Money" came out in 1994. The formula has worked well for Janet Evanovich and she has pretty much left it alone in "Explosive 18". All the characters you expect to be there are there (Stephanie, Joe, Ranger, Lulu and her arch nemesis, Joyce Barnhardt). I don't think this book is great, nor is it bad. I guess I would describe it as the same. That might sound like a criticism but I don't intend it to be. I really enjoy these books, they're good fun, and I'm not bored with the formula yet.