Duke's occupies what used to be a Captain D's, so it's not very large inside. The first thing you see walking inside is the buffet line. $10 for the all you can eat buffet (including a drink). The selection is pretty standard: hash, rice, pulled pork, fried chicken, veggies, desserts.
The BBQ is pretty good here. Not quite as good as some of the other places I've been, but pretty darn tasty. I'm sure it will only improve over time. The fried chicken was also very tasty. I can also say that out of all the BBQ places I've been to in Charleston, this place has the best mac and cheese around.
There are 3 sauces to choose from: hot and mild mustard, and vinegar. The sauces are located above the buffet, so if you forget you'll have to go back to the line. I went for the vinegar sauce this trip and thought it was pretty good. Nicely tangy without having too much of that harsh vinegary taste you sometimes get with vinegar based sauces. Goes quite well with the pulled pork. A loaf of bread is provided on each table to go along with your BBQ.
Duke's already seems to have developed a following and was pretty busy inside when I stopped by for dinner on Tuesday. There was also a steady stream of cars driving around to the take-out window. It's walking distance (a longish walk) from my house and on the way home from work, so it will probably end up being a place I go to more often than I should.