I am a sucker for Steampunk and late Victorian fantasy, but I had some reservations getting into this series given the basic premise. I had read The Watchmaker's Daughter series (through Book 3) by C.J. Archer, and while I liked the style, it was very much near historical, with the fantasy elements playing at best a very minor role. I found The Ministry of Curiosities to be very much in the same mold. The protagonist, Charlene, aka Charlie, has been living on the streets, disguised as a boy, until she was caught by the police and thrown into jail. It was then that she discovered that she had the ability to raise the dead, which she used to escape. Shortly thereafter, she was kidnapped by The Ministry of Curiosities, led by the enigmatic Lincoln Fitzroy, the organization's head.
The story, over the course of the series, is a slow meander through British society (High and Low) in the 1880s. There is magic involved, but in reality the magic serves primarily as a McGuffin, with the real story being a young woman's emergence into the highest of high society, and the quasi-historical characters that she encounters along the way.
Archer is adept at drawing out period characters, and her knowledge of 19th century England is astonishingly deep, down to the mores and expectations of the various classes. To be honest, after a while, I kind of reached a stage where I was ignoring the magic just to concentrate on the richly drawn characters.
Overall, I'd say my only real complaint is that the stories have all tended to become formulaic and to drag a bit, but for people who love good characterization, this is a gold mine.