As opposed to the previous commenters, I've visited this place twice and both times, I went to the fifth floor - where the expensive stuff is. The first time, I went for their 10-course meal as a part of the Vegan Food Tour I was a part of under O'ngo Foods. The second time, I took some friends and we ordered the 15-course meal. It's a bit pricey but the food variety and quality was well worth it - it was both eye candy and a treat for your taste buds! Obviously, you wouldn't come in regularly but if you ever have the chance, treat yourself. :)
I finally got the chance to visit the 2nd floor on my last visit to Korea... For both lunch and dinner. When asked, they reassured me that they did not use onion or garlic in any of the food (the 5th floor does unless you request them not to). This place was very informal, compared to the 5th floor. For lunch, we got the temple style buffet. You get your 4 wooden bowls and then you fill 'er up! The food isn't gourmet by any means but it is on the light side and quite delicious. They offered several sides, soup, and various kimchi. Also, they have THE best cabbage kimchi I have ever had the honor of tasting. I need the recipe!! Not salty and perfect amount of sour. There was a side dish of rather tough greens... But it definitely had a ton of fiber. Though not quite delicious, it was certainly healthy and I got seconds. ^^
For dinner, we returned and decided to order. The buffet was still offered, but there is a menu with various items, but we ordered the kimchi stew and the veggie Katsu combo. Both were delicious but my favorite was the kimchi stew. Oh goodness, my mouth still waters just thinking about it!
All in all, the 2nd floor was great. The food was delicious and reasonably priced. It's largely self-serve and help (you put up the dishes yourself after you finish). If I lived in Seoul, I'd definitely make regular visits!
Updated from previous review on Wednesday October 31, 2012
Cons: 5th floor is expensive