-The plot idea was pretty good
-The actors and actresses were amazing (main and support)
-The characters were well thought out
-The OST was nice
-The costume design was spot on and aesthetically pleasing
-The production in general was great, they paid a lot of attention to details

They were so many outstanding things about the drama that the expectations were set too high... So some aspects of the story and character development were a bit disappointing.

So... The drama was OK. Do I regret watching it? No. Could it have been better? Definitely. Would I rewatch it? Probably not. At least not in the next 5 years.