One needs to watch from the beginning to the end to fully enjoy this drama.
I have watched it several times. I love it.
Reasons:
Story- It is a unique story unlike any other Thai drama that has mainly to do with the arranged/suggested marriage.

The father left ML (Korakot) a condition (not forced) in his will suggested to marry FL (La Ong Dao - his adopted daughter) because of 2 reasons,
1. To continue to protect the princessLa Ong Dao,
2. To make sure that his stubborn and party animal son will have a loyal and loving wife that matched him. The ML can still avoid marrying FL because his father also left an exception which is up to the FL. They ended up getting together, not because of the condition in the will, but because of their real love.
Unlike any other Thai dramas, there is not much skin contact, but the feeling of love for each other is so pure, and their bickering is unique and innocent.

Acting:
The ML is super manly with deep, expressive eyes, and sexy lips. The FL holds elegant beauty and perfectly fit in this role as La Ong Dao.

ML: How he tries his best, being deeply in love with FL while being faithful to his GF (Padachamai). The way he calls FL"Dao" is so beautifully passionate. The way he looks at FL or the expression in his eyes when he is thinking about FL is priceless. He did an amazing job trying to portray a heart Broken man showing brotherly love to FL while actually deeply in love with FL (adopted sister, but hasn't met since childhood).

FL: She is just perfect. Unlike a FL in any other one sided-love story, she doesn't chase ML, she is just simply elegant, capable and well-mannered even though the ML is her first and only love of her life.