I had the option of an onsite interview or phone interview for the first round. I chose onsite. They first showed the office, which was pretty cool of course, and then I was led to a room with an interviewer. The interviewer had a very different background, and we had a brief chat and it was clear to me that despite being intimately aware with what facebook was doing for the role I was interviewing for, that topic was never touched. The interviewer did not care for my background or the role I was interviewing for. I was asked one question - I gave it my best shot. I could definitely have done better, but it was certainly annoying to be judged based on how I solved that one question, instead of a more subjective conversation based on my background.