The book is written well and the plot is decent but the characters are so flat. They are caricatures of their roles. The dialogue is so unbelievable, real people don't talk like that but "characters" do.
The villian is only a villian, purely evil and nothing redeemable. The hero is borderline psycho with how possessive he is of the heroine he barely knows and yet somehow loves. Also, so many times it's mentioned he is acting honorably just because his father would do that, why no personal sense of honour?
Likewise, the heroine is weirdly obsessed with him for no apparent reason but he motivates all her actions and dominates every thought. It gets very eye rolly. She's apparently an innocent, naive virgin yet her first assumption is they're lovers but at the same time sharing body heat is So Scandalous.
It's readable, it's just the book equivalent of a B grade horror movie, the one dimensional characters and dialogue really lets it down.