First of all, make sure you note that this store has moved and both their old locations are closed, including this one.
Their new store is crazy. It's divided up into little, unorganized, dark rooms, and it smells. Their hours are erratic and the staff is too busy doing whatever they're doing to even say a polite hello.
There are a couple great used bookstores in Columbia, so skip this one. Ed's Editions is great and there's a new store on Two Notch (in the old book dispensary location) that is really great, Books Revisited. Go there!