It's a beautiful drama that revolves around the themes of relationships, self-worth, coping with hardships in life, and the true self as opposed to the idealized self. These themes already make it very interesting, as every single character is shown as a whole person with proper depth and elaborate feelings and thoughts.
An important part of the plot, if not the most important, is deafness (and Deafness) and the many facets of it. Since I'm not deaf myself, I'd rather let actual deaf/HoH people judge whether it's good representation or not; all I can say is that it was a very interesting theme and it seemed to be explored properly and not just used as a fancy plot device.
What I liked the most about this story is that it doesn't make fun of its audience with poor writing. There is no villain because there's no need for one, and all the characters have both their perks and their flaws in good balance. All the events flow nicely without annoying decisions that don't make any sense or annoying events that are just there to make us feel bad.
The actors all did amazing. The friends felt like actual friends, the lovers felt like actual lovers, the siblings felt like true siblings, and so on. There's little to no physical touching in the entire drama, so I suggest you looking elsewhere if you're expecting passionate kisses or anything like that.
While the music is very pretty, I was mostly impressed by the use of the silence in many scenes, which make them have a bigger impact on me. The only thing I really didn't like about this drama were some abrupt cuts between one scene and the next, which were pretty jarring: at some points the music just cuts off to silence all of a sudden, which can be confusing.

Overall it was a very sweet and memorable drama, probably one of the best I've watched. If you're looking for something sweet and slow, I highly recommend watching this one.