Amazon Developer interview questions

My interview process at Amazon started when I was referred by a friend who worked there. I was then contacted by the team lead who kindly took me out to coffee and a lunch to discuss the team. To further encourage me to interview, the team lead allowed me to come in for a few hours to pair program with a couple of the developers on the team and see how their agile development process worked on a typical day. The next step was for me to do a technical phone screen. The interviewer was very nice and asked one technical question and one design question. The last step was the day long in-house interview which consisted of two one person interviews, two pair interviews, and a lunch interview. Half of the people who interviewed me were nice and patient, making the interview a conversation more than a grilling. However, the other half definitely made it feel like more of a grilling by becoming impatient (even turning red) when I wasn't giving a good answer. The team lead called me personally to tell me they decided not to hire me. Overall, I have mixed impressions from this interview. I am very grateful for the personal touch of the recruiting process and the opportunity to see the team on the inside, but I was a little taken aback by the interviewers that were a bit aggressive and frustrated when I wasn't doing well on the interview questions.