I was already an employee, and interviewed as an internal applicant. I was presented with a series of 5-6 behavioral based questions with a panel of interviewers (in this case 2, but I've had as many as 5 in the panel). The composition of the panel changes based on the level of position that you are applying to (for example, I hired in as an intern, and was interviewed over the phone by an individual senior manager).

Only made it to the first round of interviews but everyone was very nice. They did a great job of setting up the interview and was on time. Communication before and after the interview was very quick.