First the good: If you're looking for older books, you can find some good bargains here. While searching the store can be slow and tedious, the findings can be worth it. The prices aren't as good as eBay, but they are the only place to find some books.
And the bad: If you're looking to sell some older books, expect to get ripped off. You could bring in an entire box of nearly new books (perhaps $50 and > on eBay), and they will offer you at the most $3 or $4.