I'm not sure if Heyer's cant is genuine Regency slang, her own invention, or something inbetween -- I've read claims either way. I can't remember any Heyer-ish expressions from Austen, so that's an argument on the non-authentic side. But I quite like both fantasy vocabulary and unfamiliar vocabulary as part of worldbuilding, so that part of Heyer's books are fine to me.
Infodumps are also something I'm willing to tolerate. Sometimes they're even an attraction in themselves, like Pratchett's footnotes
Heyer's infodumps are more in the skim-past-to-get-back-to-the-story category, though, and I quite get why some readers find them too annoying.
I liked The Corinthian, am ambivalent on The Grand Sophy (marred by blatant antisemtism, and I didn't like the treatment of Eugenia (or whatever her name was -- the fiancee of the main male love interest)), and found An Infamous Army pretty meh. The Unknown Ajax was funny, and I also liked Venetia.
KJ Charles has written her own version of Venetia:
Band Sinister. I liked it a lot. Unlike Heyer, Charles has explicit sex in her books, that might be a drawback for some readers. (She wrote an interesting article about
consent in sex scenes, where one of her examples is from Band Sinister.)
I reread some of my Heyer favourites when I'm in the mood for something light and funny
