Keep in mind that I may be a bit biased as I am, after all, Korean. And I may judge them a bit harshly, as they tend to create abominations out of the recipes to save themselves a few pennies.
If you believe that the restaurant's food is solid for its price, I would assume that you:
1. had no previous experience with Korean food
2. you simply have never had a solid Korean food at a solid Korean restaurant.
One thing I noticed straight off the bat was the low quality of food. It'd be quite silly to set the expectation bar high in terms of quality at an All-You-Can-Eat, but the quality was just abysmal.
The pork belly tasted not only old, and they had not even gotten rid of the skin of the pork. This is purely out of laziness, and ruined the taste.
When the two soups available in the AYCE came out, I was shocked. One of the beef soup was simply the broth that is left behind when they boil the meat for their main course menu hotpots. Simply that. No other ingredients. The other soup was egg soup - again, just the egg boiled in water.
The pancake lacked any ingredients. The japchae was the biggest abomination of food I had ever seen. Instead of the marinating andthe variety of vegetables it should have (it's something like a Korean noodle salad that's served cold) it was simply this wad of noodle that had been soaked in sauce. Imagine ordering a salad at an Italian restaurant and all you got was lettuce and dressing. That's how I felt.
I will never be coming back here. As for the people who will be going back, you have my condolences, as I find it quite disturbing that they trick foreigners with their horrible food and altered-for-pennies recipes.