I interviewed after my manager suggested it to me when I was a temp. The interview was with two managers needing to fill a vacancy on each of their teams. The questions were in the behavioral question format. It's between 8-10 questions. Make sure you bring post interview questions because the managers love it. Do NOT ask about parking, lunches, anything frivolous. Ask them about their leadership style, ask what's to be expected of the position within 3 months to a year, etc.
Make sure to send them a thank you email or card since the managers will gravitate towards people who take the time to do that.
Work atmosphere at my location is friendly, managers have a great open door policy