We ordered Gangnam set. The chicken is really juicy and tender, but other items are actually too sweet that you hardly taste the meat and get sick of the sweetness really quickly. The soup and hot tea are not hot at all. Portion size is ample and can easily be for double the amount of guests they recomend. Among all the staff, only one of them is attentive and friendly. We ordered the honey toast which we waited for over 15 minutes and thought it would never be served. We also got the free deep fried banana for making this rate. I believe this is how they got all the reviews and good ratings because you have to show them the rate to get the free dessert!
In conclusion, Gangnam is an up coming trendy restaurant with modern/urban feeling if that is what you are into, but as far as Korean food, I would rather spend my money at many other great selections around the city.