I'm on a bit of a Georgette Heyer re-read kick at the moment. I started with The Foundling and went on to April Lady.
As with The Foundling, one star deducted for the main female lead. This time the star off is because of Nell's wild mood swings. As in, sometimes she's shy and awkward and lovable and all that stuff, while at other times she's sensible and mother-like and straightforward. It doesn't seem to have been done as a matter of character growth, it just seems to be...not quite as well written or consistent as most of Heyer's characters.
Cardross is really rather delightful, and is one of the first male leads I've read who, while being absolutely horrible when he's jealous and angry (for actually understandable/good reasons) apologises unreservedly in the same scene. I can't say how refreshing that is.
Heyer's books always have such a lovely cast of glorious side characters: I love her mad, bad, and downright weird secondary characters. April Lady is no exception here: Nell's brother and his friend Chubby are just delightful (if rather annoying sometimes) and Felix Heathercott is a constant stream of delight through the book.
In this one, my favourite character (out of all the characters, not just side characters) is Felix Heathercott. He's a darling. Seriously: he's quiet, sensible, very sweet, and knows just how a woman ought to dress, and how to dance with her. What's not to love?