The book imports a limited kind of magic into the time and setting of a Jane Austen novel. The magic includes variations on "glamour," changing the appearance of people and objects to the extent of creating significant works of art.
I read it almost back-to-back with Austen's Northanger Abbey, and I think MRK did an excellent job of writing in the style of the the early 1800's (not that I am really qualified to judge). I also think that writing at novel length gave MRK the space to develop her themes and characters more fully than she has done in many of the short stories of hers that I have read.
The novel had a feel of YA (a little bit of over explaining and over simplifying) and none of the sparkling acid sarcasm in Northanger Abbey. For that reason, I would personally be more interested in reading more Jane Austen instead of continuing with this series, but I wouldn't hesitate to recommend it to the right audience.