I'll say that this book in the series (goodness, how did Leon get to #22 without me noticing?) is less structured than some of her others.
The usual kerfuffle with Patta is there. The repartee with Signorina Elletra is as delightful as ever. His relationship with his clever, fun, foodie family is there, as amusing as ever. So that structure is certainly there. But the rest seemed more all over the place - probably because of how the murder landed in Brunetti's lap.
The only twists you see are related to Signorina Elletra and an unexpected plot twist regarding the victim and his family. This is actually more horrifying than usual. But not the level of horrifying from the last book, which was stomach-churning. This one is the "ineffable sadness" level of horror.