If I'm gonna write one review per year then utsukare is my choice for 2021

I would have completely bypassed this drama if it wasn't for Yusei, but I was hooked from the first episode.

I have 0 knowledge of the novel so I'm judging this drama as it is. I think defending any criticism of the drama using the novel only devalues the drama production and its actors. A successful adaptation should be able to stand on its own. And this one does.

Is this drama for you?
- both protagonists are realistically flawed so if you prefer your characters to come out the gate perfect then this drama is not for you.
- writing is subtle so if you prefer to be spoon-fed then this drama is not for you.

regarding the 3 major points of contention among the (western) audience:
1. English translation of the Japanese expression kimoi/kimochi warui
Meaning changes based on context so it's not always "gross". But even in the infamous episode 1 regardless of the translation, Kiyoi saying it was valid because one should be allowed to express their discomfort at someone who's clearly acting out of pocket towards them.

2. hate boner for Kiyoi
Kiyoi is neither abusive nor a bully. You can call him bully-adjacent if you are pressed enough, for hanging around bullies and allowing some behaviour to happen, but Kiyoi who wants to keep his unbothered prince image, behaves subtly. Typical protagonist when witnessing bullying would jump into the fray with their chest puffed and full of self-righteous attitude. On the other hand, Kiyoi's behaviour is nonchalant but gets the job done, nonetheless. Making Hira be part of Kiyoi's clique is like having a pilot fish keep close to a shark because it offers protection from other predators.
Anyway, most of the story is told from Hira's POV and when it switches to Kiyoi we see that things are not as they seem although the clues were already there since the beginning.

3. they are toxic together
They are unconventional together, but they are not toxic. Being in a toxic relationship/friendship/whatever makes one or both parties deteriorate, mentally and in other ways. I wish people would stop assigning terms like that to whatever doesn't fit their ideal.
There is a power imbalance (created by Hira) but Kiyoi does not take advantage of Hira's willingness to do absolutely everything for him, beyond basic errands. Ultimately, they don't have a negative effect on one another, and they are not worse off together than they would be separately/with other people. Hero worship and subpar communication skills are their biggest obstacles and it's something they must overcome to be together.

I think both are multifaceted and interesting characters. A couple of young messy teenagers who are insecure, lonely and bad at expressing themselves and deal with those issues differently.
Kiyoi who keeps people at arm's length and hides his weaknesses behind a harsh exterior meets Hira and wants to open up to him. However, Hira, bullied since childhood which made him shut off from the world, tends to live inside his own head so it's hard to get through to him.

Performance wise, Riku and Yusei did a stellar job. Riku balanced the awkward and the disturbing well, while Yusei has very expressive eyes and knows how to use them like a weapon. Their acting in the final episode was especially good. I fully expected Riku to nail his scenes but Yusei surprised me. As a certified JrExile fan I have watched other projects with him like Mannequin Night Fever and Back to the Memories, but Kiyoi's character was complex, and Yusei rose to the occasion.

Rewatch value is high because for a drama as subtle as this the devil is in the details.