"To start with, this is a great theme, a lot of clever and varied costumes. I've personally had fun taking photos of the police officer accosting the other minifigs for various misdemeanors (not the point of the theme but, hey, they were funny).
So why the low score? Well, up to this point (excluding series 10 which suffered the same issue) a person was guaranteed to find three complete sets of minifigures to a box, with some extra depending on the number of different minifigs in the series. Unfortunately, in this series, there is a limit of one police officer to every box. While not the most interesting of figures, it still makes obtaining him a chore at best, expensive at worst as people take advantage of the artificial scarcity and people's obsessions for completing their collections by charging ten times the retail value (at least).
While series 18 is a celebration of 40 years of minifigures, the guest of honour won't be appearing at most of the parties. Who would have thought it, the one time you want a police officer to turn up to your party..."