I couldn't resist the opportunity to use this title, haha. This series is nuts! Overall, I really enjoyed it, although I had no idea what was going on for the first few episodes. It's funny, engaging, and ultimately hopeful. I particularly liked the empathy with which the main character's mental illness was portrayed. It also doesn't hurt that K is pretty cute!
I took a couple of points off because I found the plot difficult to follow at times and some of the things that happened involving Ryu Su-yeol and K didn't really make sense, but if you suspend your disbelief a little then it's an entertaining ride.