Although I've never been much of a fan of crime series or novels, I confess that I do like Agatha Christie's Hercule Poirot and Miss Marple both on the page and on TV. Miss Fisher is of the similar stock, but with a slightly lighter and fashionable twist. I think the episodes are well written and the set design and the costumes are true to the period.
Pictures from the ABC TV web site, no copyright infringement intended.
It's strange, really, the 20s fashion seems to be an acquired taste; I didn't really use to like it before (except the hats and the shoes), but now after a lot of exposure I've begun to see what's so great about the twenties style. I still adore the hats and the shoes, and the gorgeous fabrics and embroideries are another thin.
So, if you have a chance, I recommend Miss Fisher, even if it's only for the fabulous clothes :)