This is was a let down. The beginning is great, fun and cute, but then starts getting so bad and mostly annoying. I was excited for the portrayal of adult friendships and even the moments the kids share. But then everyone shows they suck as friends and sometimes as a person that it's so annoying.
Everyone is so unfair with Dae-Oh, who is the only truly good character in the whole show that I was mad at all the other characters.

[spoiler] the moment is destroying the books because he knows the truth is so moving. Mostly was not his fault and he's suffering like that and trying to get things right anyway. Although is sad, it's my favorite moment in the show. His despair is so heartbreaking. [/spoiler]
For me, he was the best thing about the show, one of the few saving graces.

Ae Jung is just so unfair, arrogant and just to snob... I get the misunderstanding but even after the reveal
[spoiler]that NOTHING is Dae-Oh fault, she doesn't apologize and tells him the truth about eveything [/spoiler]
and the daughter, OMG. It's jut so annoying and unfair just like the mother. Ryu Jin is another character that got me so mad, What a shitty friend! He saw is friend suffer all those years and he has some fault in the misunderstanding and again... not even one apology, nothing. How can everyone be bads persons like that!??!?!

Sook-He, Paa Do and even A-Rin have really good moments, but not enough screen time, sadly. They would be great to have more time with, since they don't suck like some of the mains.

The cast is good, some hilarious and some heartbreaking moments, but in the end... Oh Dae Oh deserved better and that gets me so mad that I can't recomend this show.