I just read this last week! I really enjoyed it for the same reasons you did -- framing devices, the empress and the handmaiden's relationship, every instance of people and traditions unvalued/unappreciated by the empire being used in the rebellion. I *did* wish this was a whole novel instead of a novella, because some events would have hit harder given more page space devoted to fleshing out certain relationships, but it does mostly work and there is a sequel coming, so overall I'm pretty satisfied.