First let me say that this review could be biased since I personally like the cast so much. But seeing the positive ratings from pretty much most of the people watching this drama, I hope that this review could relate to most.

Story, the story is so good. Perhaps saying that it is just good can't possibly show how good it is. This drama doesn't only provide entertainment, but also a lot of hidden messages that have meanings where we can relate in real life. I thought at first that it would be like 18 Again, but instead this drama actually went back in time and instead of the dad being the lead, the son will try to change his dad's fate and make sure that his dad would not change his love interest whilst also trying to prevent him from getting into the accident that made him lose his hearing. (My prediction is that I think him preventing his dad's accident is so when he returns to his timeline, he wants to perform in front of his dad knowing he could hear the music he's playing). The best quote on this drama is where Balsan shares what HEG has been doing for HYC without him knowing and says that he almost cried when he said,

"I want him to shine. First, on the stage. Then in life."
- Ha Eun Gyeol

Casting, there is no other words I can use to describe HOW each and everyone FITS exactly where they should be. I can't even imagine anybody else playing the main roles other than them. Both couples, Ryeorina (Ryeoun and Seorina) and Hyunsoo (CHW and SES)'s chemistry is so good. Even though I ship Ryeoun and Eun Soo more than... nvm since it would've been weird if the drama took that turn.

Music, I personally like both the OSTs and songs covered or used in this drama. For the OSTs a few that I personally liked the most is A Song For You by Joonil Joon, and Higher by JU-NE. But this drama also features Canon Rock, Walking to Heaven by Jang Hyunchul but I think in the drama they used Song Jin Wook's rock version, and much more (including their band's songs like Shining, etc).

Rewatch Value, I can't tell you how many times I've watched this drama from episode 1-8 while waiting for the 2 new episodes each week. I would rewatch this drama over and over again since I can't wait for the next episode. (And this is during my mid term exams as well..).

10/10 for me. If I could rate it higher I would.

UPDATE:
I just finished it and currently in the middle of debating whether I should be happy or sad that it's over. Even though in my head I had thought of a very different ending,
*SPOILER*
I half hoped that the accident that HYC had in episode 15 wouldn't be the same as what had happened before and he wouldn't be deaf, and the ending would've been them (HEG's band) performing in front of him and him being proud of his son's band.
*END OF SPOILER*
but the ending that happened in the drama didn't disappoint me at all, but I think that this is one of the most acceptable happy endings and didn't make me change the rating for it. Personally I felt that the ending was quite rushed, since a few things haven't been cleared up (Such as OEY's trip back, HYC's coping mechanism to his new condition, HYC and YCA's love story after the accident, and the band's fate ). But still a well deserved 10/10 drama near the end of 2023. Hoping that this drama would bring a few awards back home to either the production crew or the acting casts since this was a blast.

Currently waiting for Sweet Home S2, Squid Game S2, and All Of Us Are Dead S2 and hoping that they would come sooner and not end up as a disappointing season 2.

Dictionary for the Abbreviations:
1. HEG - Ha Eun Gyeol
2. HYC - Ha Yi Chan
3. YCA - Yoon Chung Ah
4. OEY - Oh Eun Yu
5. CHW - Choi Hyun Wook
6. SES - Shin Eun Soo