This is one of my all time fave by now. I don't know what else to say, most of the reviews here already listed everything nice about this show so, Here are some of my favorite thing about this show:

Acting : You would never have guessed that this is Mix's first acting role, his subtle expression and change of emotion are really good. You can really see he's acting just with his eyes, for example the hornbill scene when chief asked "Romantic?" you see his expression changed from happy to shy/awkward just with his eyes. Same with Earth they both complimented and elevated each other here. CHEMISTRY IS TOP-NOTCHED.

Music : OST is really good, you can never get tired of it even with 3 versions of the same song. Other songs used are really chosen well, especially with the incorporation of WIND which makes it feel like they're all connected. I've listened to the shows track on repeat since it ended, every time you hear it it gives you that nostalgic feeling of the show.

Story: The heart transplant plot has definitely been done before but the show took a fresh take on it. Other viewers were afraid that they would fall in love because of Torfun's heart (maybe chief liked Torfun before she died) but they pretty much made it clear that it wasn't the case. The heart transplant was used mostly to progress Tians character development, to make him a better person.

Rewatch Value: I've been rewatching this since it ended since i've been missing the characters. Still gives me all the feels.

HIGHLY RECOMMENDED.