I know this one came out of the Candy Bowl last year, but I'm counting this one as my first book of 2015.
I love the descriptions of the fashions of the time and of the people and the buildings, though occasionally the author gets a bit enthusiastic and it tips over into info-dumping. I'm quite happy to go and find out more by myself rather than have the description get in the way of the story.
And talking of the story; it's got everything you could wish for. Rakes and mistresses, impoverished heroines, lovelorn heroes, domineering matriarchs, and more dukes and nobles than you could shake a stick at. And lots of sex. (Which explains why my mum hid this book from me many years ago.)