First rounds were pretty basic. They just asked me about my resume, not a whole lot of behavioral questions. Mild case questions, just "walk me through your line of thought," style. The second rounds, in their Seattle offices, were intense. They were very probing into behavioral interview stories, and they asked lots of case questions. They were not super clear about what things meant - I've also interviewed with consulting firms, known for difficult case questions, and I've found their approach more straightforward than Amazons. I think their interviewers are told to be tough.