Read: Feet of Clay
Feet of Clay must be one the pun-niest Discworld novel in the series so far (that is until book 19). It's a decent mystery novel and a great installment of the City Watch sub-series.
Discrimination, stereotyping, gender (identity), exploitation of the worker class, politics, governance, and the social contract: All this in a fantasy novel.
Most important (for my personal enjoyment of the novel), however, is that I absolutely loved the stabs at religion.