At first, I didn't like the drama because they said it was a sad ending. But when my cousin recommended me this, and she said this is one of her top 1 favorite so far. Then I feel curious about it and I started watching it and it hooked me. Actually I didn't binge watch this, I finished it within one month because I'm not ready for the ending HAHAHA and also I have a lot of school works, so I cannot binge it. I only give 9 on re watch value because every time I saw this it hurts me too much
Here are the things that you need to know:
1. Good plot twist
2. The ending of each episode made me want to watch on the next episode (Gladly I can handle it because of too many school works HAHAHAHA)
3. You need to bring tissue or water on the last episodes especially if you are an emotional person (like me) I swear I'm not joking.
4. You cannot move on after watching the last episode, again if your an emotional person you can't get over it, your still crying over it.
5. There might be a tendency that you feel the characters make you angry except for No Eul (Bae Suzy). She is a very strong woman, no matter people hate her or discriminate her she is still continuing on her life and to stay strong. She inspires me a lot.
6. This is a heavy drama
7. Some people say that they don't feel interested on the first few episodes but for me it's not... The first few episodes make me hooked more.
8. You will fall for Kim Woo bin HAHAHAHA before he is not my type actually I don't feel a second lead syndrome on" the heirs" But when I watched this, GOSH! I was wrong, he is really handsome and a good actor!
9. Great Chemistry!

This is all that I can say! Overall I enjoyed it! I hope this helps for you