The K2 and Memories of the Alhambra - never really watched that but I heard a lot of people not being satisfied with how things went with it, especially MOTA.
Goblin - people generally enjoy it and yes, it's a good drama (at least the first half). I didn't really help that I'm uncomfortable with the pairing of the main leads. Too much age gap with the characters (female is a high school student while male is a 400 year old soul).