In my opinion this book consists of two components. 
 First component are dialogues between Annis and Oliver. They last for many pages. I can't recall if there is another book of Heyer where are so long talks between main hero and heroine. And let me tell you, this talks are fantastic and amusing. There wasn't a force which could have forced me to take a break when I was reading one of this dialogues. 
 Second component are monologues of Miss Farlow. I almost envied her the capability to this chatter. I read it spellbound and with a big smile on my mouth. The ease with which she goes from one thing to the other - I couldn't invent it. Heyer was a master. 
 Between this two components we have Bath atmosphere, a little about change from a boy to a man and of course a little about society. But these are additions. One of the surprises is that (view spoiler)[we don't know if Lucilla and Ninian will be together. In all Heyer's books I have read until now all love stories (not only main) have endings. This is the first time with this big unknown. (hide spoiler)] But it makes the book more unique. 
 I don't put it on my shelf with the best Heyer's Regency romances but just behind them.