I went straight to regional interview level. Interview consisted of two behavioral interview and a work flow. Work flow requires basic math skills and some stochiometric type conversions. Behavioral questions focus on leadership experiences and situational questions. If you look up Amazon's leadership principles and tailor your answers/experiences to fit nicely with these principles, then you should do well with these types of questions. Work flow is a 'get it or you don't' kind of question. If you seem shaky on the math, they may ask you some follow up questions altering the situation a bit to test your ability to further quantitatively analyze the situation.

Very straightforward and standard interview. Met with two managers and they were able to answer my questions regarding the position. Decided to decline due to another opportunity but would recommend.