Informal, one-on-one interview with a manager and standard interview questions going off of the information provided in my application. Also, lots of question/discussion about books, of course: favorite genres, favorite authors, what book I'd read most recently, etc. It wasn't high pressure, and I actually found it pretty fun.
The manager seemed uncomfortable with my level of education though, since I already had a bachelors in hand. I had just started graduate school at the time and was looking for a part-time position to last me through the 2-3 years of my program. Even though I said I expected to stay for at least two years, she said she was concerned I would leave them early. I did not get an offer.