I 100% agree with TOP, Kim Hye Sung, and Kim Bum's casting, but I disagree with the rest. An actor's personality should have nothing to do with their casting, but rather their acting ability.
In my opinion, IU is an OK actor, but I'd cast Baek Jin Hee for this role. She's cute, but definitely has some boyish charms when she sports short hair (as seen in The Secret Garden).
There are very few twins to pick from in Korea, so I'm not sure who I would choose for Hitachiin twins, but I don't think it would be the Jo twins. I have doubts about their ability to act as two of the lead roles.
As for Tamaki, again, I'm not so sure about Leeteuk's acting ability, and anyone can dye their hair blonde. I'd cast Jang Keun Suk for he has experience playing vain characters and can be over the top, as Tamaki often was. I'd maybe even cast Hongki because he can act and is good with situational comedy.
I usually always find myself rooting for the second lead. It's just so hard to not like them and want them to be happy! Especially Shinwoo in You're Beautiful.
In my opinion, IU is an OK actor, but I'd cast Baek Jin Hee for this role. She's cute, but definitely has some boyish charms when she sports short hair (as seen in The Secret Garden).
There are very few twins to pick from in Korea, so I'm not sure who I would choose for Hitachiin twins, but I don't think it would be the Jo twins. I have doubts about their ability to act as two of the lead roles.
As for Tamaki, again, I'm not so sure about Leeteuk's acting ability, and anyone can dye their hair blonde. I'd cast Jang Keun Suk for he has experience playing vain characters and can be over the top, as Tamaki often was. I'd maybe even cast Hongki because he can act and is good with situational comedy.