Very long interview process. Steps were: Initial phone screening with HR, first interview with hiring manager, case study, aptitude/numerical test, and then final interviews (6 back to back on the same day).
One of the final interviews is with a "bar raiser" who is a senior employee at Amazon and not part of the team but has the final say on the candidate.
Make sure you have lots of examples.. and don't repeat the same example in any of the interviews. The interviewers will compare notes too make sure you're using unique examples.