...when I hate this place. The majority of the humanities professors at Penn assign books from this store (in rebellion to the large happily corporate Penn Bookstore) resulting in the fact that the store is extremely crowded with students, weighed down by ten pounds of books a class for a full week. No used books are available, and at least one of the school-funded payment methods (I can't remember which) is not available. Furthermore, it is impossible to return a book here without showing proof of having dropped the class and other such complications. However, I will vouch for the fact that they kindly keep their class-room inventory longer than expected.
Outside of the rush of the start of class, this is a friendly, if of a liberal bent, independent bookstore, calmer and with a good table for browsing. It well suits the atmosphere of Sansom Street on these days. Those others though...surely color my memories more than they should. If anything, attempt to buy books during the middle of the day and be prepared to wait!