I was impressed with how quickly they contacted me for an interview and started the process. From the very beginning, Amazon pushes how they think they're very different and that their interview process is something you should cram for.
I spoke with the initial recruiter, then a couple of peers about a week later, then more peers about two weeks after that, and then a 4-hour long panel interview two or three weeks later.
The entire process was probably a bit longer than 10 hours total. The questions and process themselves weren't terribly difficult, but it was obvious with some of the interviewers that they were quizzing you on the prep material that was sent when the process started.
The whole thing felt convoluted. By the time the process was over, I was more irritated than excited. Ultimately, I was offered a different position, which I turned down.
When I asked for feedback as to why I had been offered a different position, they wouldn't say a word. Pretty lame, when you've invested that kind of time into an interview process.