Pretty much everything's already been said about this drama, so I'll just give a few thoughts.
STORY: Not a 10 because there were a few minor plotholes and I was a little miffed at the conclusions of some of the couples. But it was definitely new and different, and unlike most fantasy dramas completely explained everything viewers needed to know about the world the drama was set in. Characters were fleshed out more than usual, and the leads weren't perfect but they were wonderful anyway.
ACTING: Mark Chao is my new obsession. They need to cast him as Li Shang in Mulan, or I will never forgive Disney. His Ye Hua was cold, courageous, and noble, but also sensitive, understanding, and fair. Yang Mi was spunky without coming off as immature or annoying. And everyone else was simply wonderful.
MUSIC: Downright gorgeous.
REWATCH VALUE: Not a 10 just because it's 58 episodes and I don't think I'd ever be able to manage that more than once without skipping. But it certainly has enough intrigue and story to keep you entertained for more than one viewing.