Very friendly and open. The process emphasized problem-solving and interpersonal skills, with less focus on technical minutiae. The initial interview was pure code, but without 'gotcha' questions.

The on-site interview consisted of four one-hour sessions. Each session had either one or two interviewers (the second being a shadow interviewer in training). Fifteen minutes were dedicated to algorithms, and forty-five minutes to problem-solving. (One session was exclusively problem-solving).

The only drawback was the compressed schedule, with no breaks between sessions except for lunch, which was with another employee.

I was recalibrated afterward and had to complete an additional phone interview. I scored highly on a newly added question, leading to a re-interview on the question it replaced. This ultimately resulted in an improved offer.

Throughout the entire process, everyone involved was friendly, open, and helpful within appropriate limits.

I won't answer this because it's covered by an NDA and it wouldn't do you any good.

I will say that most of the questions are thought-provoking and have no one right answer.

Facebook's recruiters will give you lots of excellent advice for preparation. Their goal is to find good people, not trip people up on dumb stuff.