Honestly I was mostly confused throughout this whole movie- I went into with no expectations (and mainly watched it because of Rain... because why not?), other reviews said this movie was for people who enjoy quirky, out there entertainment, and that's normally not me, but I thought I'd give it a try. I can see how others would like this a lot, and I didn't dislike this movie in the slightest- I just didn't really understand it.
The character development was consistently good throughout the film with the two leads. The ML was extremely adorable, and I liked how the FL grew as a person throughout the movie, but that's really all I would say. There's not much of a story line and it seems to jump around a bit, so I wouldn't recommend this to anybody who doesn't know what they're getting into.
The romance was well slotted in, there wasn't a lot of it but when it was there it was well written and acted. Park Il Son made me swoon, and the FL naivety was well placed too.
One thing I will say is that the acting was really good, they characters were complex, and it looked like they would have been difficult to portray, but it was really well done. Throughout the movie I forgot that the man I was looking at was Rain, and started the think of him as Park Il Son.
Overall I would say, yeah, totally go watch this movie, but go into it with an open mind. I won't criticise it because in theory it was a good movie and I liked most parts, but it just was not to my taste.