First the bright side.
Acting:-
I may give 15/10 if possible. I first decided to watch because JI Chang Wook looked extra cute here, but on second thought I think that is because he understood the Ri-Eul well, the always-bright magician with concrete faith in magic. Then there are Choi Sung Eun(Yoon Ah Yi) and Hwang In Youp(Na Il Deung). Both did an amazing job conveying all the emotions.
Music:-
I gave 7/10 to music not because of the songs it has. I pretty much skipped all the songs. What I admire is the background music. It toned perfectly with the emotions it was dealing with at the moment. That element added a lot of meaning to the drama.

Now not-so-bright part.
it looks magical, but is it really? There are several occasions where Ri-Eul( the magician ) gives some temporary peace to the disturbed minds of YAY and NID with his dazzling and cheerful magic. But in my pov, the drama is about the cause of those disturbed minds.
Throughout the drama, it points out how disappointing the majority of the "adults" (the left out ones are the father of two girls and the first love of Ri-Eul) are and how much they fail to protect the little lives around them.
The drama addresses several social issues in subtle yet powerful ways such as, how bad parental influence can be, the consequences of neglecting to give the mind a bit of rest, irresponsible parents, and partial teachers.
My advice is if you are looking for a drama that can cheer you up and keep your mind at ease, this is not your cup of tea. Very addicting so start watching only if you are ready to see and understand the brutality of society for can leave you depressed for several hours straight.