Lengthy and very in depth, but transparent and enjoyable. I've never met so many people who ask such deep questions that really assess who you are as a person. Granted, I was interviewing for a services role, so that experience doesn't necessarily translate to other orgs (not saying it doesn't!). On the whole, be prepared to explain any statement you make. "You say you want to be a manager in two years? Tell us more about that." Those questions aren't about trying to trick you, but to try to get a better understanding of who you are, how you think about things, and your ability to communicate. I've listed the interview difficulty as "very difficult" because I know that it's so much more in depth that other places' processes. That said, I don't think it was that difficult because the interviewers really made the interviews conversational. Fortunately I had answers for those follow up "why" questions. Definitely think about those before you interview, because if you don't, they will be extremely difficult. I did a lot of interactive activities (think role plays, etc.) to demonstrate skill sets in addition to seven half hour interviews and a phone screening.