Labyrith Books is a true book store, unlike what you'll find at the mammoth sized Barnes & Noble type stores that clutter this city. If you are looking for a store with reasonable prices, friendly (and knowledgable!) staff and lots of great books, this is the place. It has that old New York feel, cluttered with books of all types, from the textbooks for Columbia students to the newest novels and autobiographies. If they don't have it, the staff is happy to order it for you.
If you aren't a Columbia student seeking your course's textbooks, I'd try to avoid Labyrinth in the first week or two of September and in the last week or so of January, when the semester starts up and students fill the place to the brims as they buy their books (although Columbia has a bookstore, many professors like Labyrinth for its friendliness and willingness to accomodate, so many courses have their books here only).
If you are looking for a place with big cushy chairs to read a book before you even buy it (all while sipping your latte from the Starbucks upstairs), this isn't it. If you are looking for a place that knows and really cares about books, though, this is it. And if you really need that latte to make your book-buying complete, there's a Starbucks two blocks away.