Story:
Really different way of approaching a story about regrets and it was definitely handled well. The only complaint that I'm sure many will have is that the opening scene of every episode starts to get repetitive and boring.

Acting:
Fantastic acting from all the members who made each character stick out even if their role was limited. Can't think of a single actor messing up.

Music:
Perfect and wonderful to listen to.

Overall:
This drama was really exceptional and although the opening scenes were a disappointment, the whole story in itself was beautiful. The chemistry between the all the characters was incredible and sometimes got me reminiscing about my high school days. Watch it!

PS - the special is coming out soon in 2008. Can't wait! :D