As someone who grew up on Korean cuisine, I was delighted when I came to the U of I campus and discovered what could be called a plethora of Korean restaurants. Out of all that I have eaten at (and I've eaten at pretty much all of them), my favourite is by far Woori Jib.
The dining room, if you would like to call it that, is spacious enough to accomodate its customers. There's really nothing fancy about the interior, but that has no bearing on the food.
The menu has a great selection, featuring a large variety of Korean food, from meat to noodles to soups to rice dishes and everything in between. The food is well-prepared and cooked upon order, guaranteeing a fresh meal. Prices are fair considering the quality of food, but it is a little inconvenient that they do not accept credit card, so make sure you have cash on you when heading out to Woori Jib.
The service is prompt (it takes no more than 15 minutes for food to be fully prepared) and extremely friendly and helpful. Menu is written in Korean with Englih translations available for those who can't read hangul or for those that would like a description for foods they have never tried before.