I also enjoyed Nice Guy. Great acting by all the actors and the writer did a great job in character development. I was dreading that the female lead was going to deal with amnesia, which is one of those K-Drama cliche plot devices, but this drama actually did a good job incorporating it into the story line and it actually played a key role in the development of the two leads.
I like the writer didn't also make the villain a straight villain, but a person dealing with lots of different internal conflicts.
I'm currently going through
"Will it Snow for Christmas," which is the last drama by the same writer. You can really catch this writer's style after watching a couple of her dramas. I like she doesn't just focus on the leads in the dramas, but develops strong storylines for the secondary characters as well. (Also it's worth noting the actor who was the lead in Nice Guy (Song Joong Ki) has a small, but important, role in this drama as well). And again in this drama, "the villain" is not strictly a bad guy, but rather a foil for the male lead.
Finally, if you want to see more of Song Joong Ki, he was recently in a music video and his acting is spot on. The story is actually sort of sad; I know I shed a tear or two when I first watched it:
http://www.youtube.com/watch?v=x4eVFXT9eIw
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