Mixed emotions on this one. Watched it because it's so highly rated and raved about but I was skeptical (high ratings are sometimes a warning sign that it just features a popular actor/actress and isn't necessarily a good show).

I liked:
No distracting love triangles. Just straight "I like you and only you"
The emotional story of the Onew as Lee Chi-hoon (so good!!!)
Chemistry between all the couples
Beautiful scenery
Bromance between male leads
It was well acted and well directed (mostly)
"Happy" ending (I hope that's not a spoiler)

However, I felt the story was actually a little weak creatively, a bit repetitive, and forced. I am not sure if I actually liked it or just enjoyed it. It wasn't a knockout or particularly memorable but wasn't a total waste of time either.