This is a genuinely good story. From what I've seen in comments and such, I think there was a bad translation or some people misunderstood Amber's condition But if you watch a good translation and also if you understand Amber's condition, I think only then can this story really be appreciated. Here's my breakdown;

THE GOOD;
- The acting is great, the chemistry is great, no complaints about anyone. Not about the friendships or pairings.
- The pace for this was GREAT. Some people said it was slow but I disagree. The topic of this series was not something where the main couple needed to fall in love in a heartbeat. It would have been unfitting. I was very glad there was no abrupt or premature romantic physical interaction. This story included a pretty complicated situation and it was handled well.
- Original story idea in this genre, very refreshing. I admit I started to figure out Amber's situation around episode 5, the hints they were dropping were not that small after all, but yet it was still quite subtle in its own way.
- Overall music and atmosphere of the show was suitable.

I have no 'BAD' or 'UGLY' to mention, so I will just address;
THE SHORTFALL;
- It was not explained well enough that Amber is intersex. In the translation I watched, Amber explains to Yu-He that he 'was always male' and that he was born with a 'chromosome abnormality'. To me, this made it obvious he was intersex-genetically male, but in general, it doesn't explain much to a general audience. Even though some people would know what he meant, I think the show would have benefited from explaining it to all viewers more clearly.
I think though, that maybe they kept it vague because explaining too technically would have ruined the atmosphere of the show for some, so it was a double edged sword in that way.

It's barely a shortfall though, because I still thoroughly enjoyed this. I was feeling feels, especially in episode 11, man. Damn.

Side note about Amber for anyone who wants to read:
Amber was born intersex-genetically male, which means he was likely born with ambiguous genitalia which appeared more female than male. In the show he says 'I have a chromosome abnormality which was why I looked like a girl'. I think he was not referring to his outward appearance of dresses and long hair, he was referring to something more specific. So after being examined by doctors as a child, they probably realized the outside didn't match the inside (i.e; genitalia appeared more female but internally he was male). He also says something about learning how to be a real male, so I assume the 'treatment' he underwent likely referred to the process (both mental and physical) of making his genetic male sex status more predominant, since he'd been raised as a girl for several years.
For more info, if your interested, Google 46,XY DSD.

This is a good show, I'd enjoy a sequel if they make one, but it's fine as it is.