Uh boy! Pratchett goes to the time and place he is most nerdy about: Early Victorian London.
The book is so charming and wonderful and funny (different humour, even more enjoyable?). It is littered with actual people from that time, both well-known (Charlie and Victoria), and little-known (which makes them even more fascinating). I should have read this one much earlier, and I enjoyed it a lot.
And of course, as per usual, most characters are not stupid at all. They do the best they can in their circumstances, according to their values, and are surprised when other people have other values or other circumstances. Dodger is self-aware and intelligent and that has been tellingly refreshing.