The title combined with a cover of a beautiful girl in a frothy pink dress made me fear this would be one of those YA novels where the 'curse' is that the main character is unbearably special and can't choose between all the many hot guys who are in love with her.
I picked it up because Kristen Cashore recommended it on her blog here, and even with the proviso that she and the author are friends, I was willing to give it a try.
The title is a sort of clever sleight of hand. I hadn't heard the term before, but 'the winner's curse' has a precise meaning, to do with auctions. Here's the wikipedia page, which defines the winner's curse thusly:
"In short, the winner's curse says that in such an auction, the winner will tend to overpay. The winner may overpay or be "cursed" in one of two ways: 1) the winning bid exceeds the value of the auctioned asset such that the winner is worse off in absolute terms; or 2) the value of the asset is less than the bidder anticipated, so the bidder may still have a net gain but will be worse off than anticipated."
So the protagonist, Kestrel--yes, she's a beautiful girl who has her pick of men--finds herself experiencing the winner's curse when she impulsively buys a slave, Arin, at auction. She pays a ludicrous amount of money and is immediately ashamed; what's more, she becomes the owner of a human being who resents his position and consequently loathes her, in particular.
There is a romance between Kestrel and Arin. To give Rutkoski credit, the first and most essential theme is that romance is literally impossible between a master and a slave. Nothing that Kestrel does makes slavery any more palatable to Arin. Nothing that Arin feels for Kestrel makes him any less determined to violently overthrow the conquerors who enslaved him (which is to say Kestrel, whose father is a talented general, and her people).
The book has a lot of twists and turns. Kestrel is a satisfyingly clever, strategic thinker who schemes her way through some very tricky situations. The romance is dominant, and I wished it had taken more of a back seat, but the writing is excellent.