My overall experience was incredibly good.
I got contacted via LinkedIn. The whole process took around 3 months. I had several phone interviews, first to talk generally about the role, my visa situation, etc., and then 2 technical phone interviews. The technical interviews were there to test my technical level, they were relevant to the role. Beside the fact that all my interviewers were nice, nothing special.
After I passed the phone interviews, I got invited for on-site interviews. Amazon paid for my flight, hotel and meals. The interviewers were, again, very nice, professional, respectful. Half of the questions were 'behavioral' questions to test how I responded to specific challenges that I encountered in the past. The other half were technical questions/exercises.
After I finished my interview day, I had the great feeling that Amazon knew exactly what I was capable of and my limits. And for me, I knew exactly what to expect with the role. No surprise on either side. I think that Amazon's interview process is extremely efficient and fair.
I got an answer 2 days after that. Not having to wait forever for an answer is rare enough to be noted.
Of all the interviews I have done (Apple, IBM, Google, and smaller companies), this was, by far, the best experience.