This is middling. The concept is quite good - a militant daughter infiltrates the enemy nation to get revenge for her father, and an enigmatic enemy prince who is maybe kind, maybe ruthless, probably both.
My problem was in the specifics of the execution. The details of when she wants to assassinate someone, when she's shy vs when she's defiant, making deals with the prince but also waffling about trusting him... it all just felt too unrealistic.
Overall, if I was more bored I might continue the series, but as is, I wasn't hooked enough to want to keep reading.