no one knows if its good yet but i guess we can make assumptions. IU is known for only choosing wonderful scripts and after BWS massive success in LR, there is no way he would choose a bad script. Also, this script has already won awards.
by episode two i was saying "this is ridiculous" every 20 minutes... but yes. i watched it till the end. the ridiculousness was that good. it was so mind bogglingly stupid that it was good. also, the actors did absolutely phenomenal.