It was nice, as far as job interviews go. Those I interviewed with were not overly formal- they were friendly and conversation was engaging; they seemed interested in really getting to know my interests, relevant job experience and world views, as opposed to "describe one time when you had a problem and how did you fix it..." type questions. There may have been some of that, but it definitely felt like more of a conversation than a formal interview.
The one challenging piece was after the interview they had a computer assignment I had to complete.