I don't think anyone who has watched a decent number of j-drama would be surprised by this movie. Fairly standard set up with an over protective brother who is secretly in love with his sister. The sister was confused about her feelings both because of the brother's love-hate behaviour as well as the taboo nature if she was attracted to him. Obviously, the drama can only go for the sad ending or a happy ending so I won't spoil it for you.
The acting was fine. A bit of overacting was to be expected. Music was un-intrusive. The OTP chemistry was quite good and they look cute together. More so than the FL/2ML pairing. Rewatch value is good.