I agree with Rachel. I stepped into this bookstore on a whim after visiting the West Side Market and I'm glad I did. The staff was friendly, but low-key enough to leave me alone to peruse the shelves as long as I wanted.
This probably isn't the best place to go if you're looking for a specific book, because there's a good chance they don't have it. But if you like to wander through the aisles and just explore, this place is perfect for that. I ended up getting four completely random books (on cooking, detoxing, meditation, and psychology) for $16. Definitely a fun place to go on a Saturday afternoon.