Besides Yeon Joo and Kang Chul being one of my favorite couple, the drama is absolutely stunning with all the elements of humour, mystery and romance in right amount. Both Hyo Joo and Jong Suk have a wonderful chemistry, my favorite character being Park Bong Soo :-D The change between the real world and the cartoon world portraited really well although the storyline could have been better.
I have already rewatched it for like three times and loved it each time. I personally think it should have a rating of 9 or above. A must watch drama for everyone.