Amazon's interview process is extremely methodical and the recruiters keep you very informed about the process and expected turnaround times (which they kept to!). There are typically two phone interviews following the initial recruiter conversation which may be followed with a half-day onsite interview with 5-6 people. Amazon is quite serious about and committed to their leadership principles and all their interview questions will be behavioral questions designed around these principles. If you interview here, I strongly recommend familiarizing yourself with their principles first (which can be found on the web).