I went through a two-stage interview process which was informative, friendly, and expedient. I did not feel rushed, but it didn't take forever either. When you first get into the office and sit in the chair in front of your interviewer he makes you feel at ease, but lets you know what you can expect at the company: hard work, dedication, and of course a warm atmosphere.
Very good personalities all around, from the application process, interview scheduling, to the actual interview itself. It was obvious from the first meeting that this company wasn't going to hire bad characters. They want you for you and your ethics, not a drone like at other places. I was also told that they promote from within-- meaning that your experience at the company is paramount. If you meet them half-way, they'll meet you!
In other interviews I felt somewhat left in the dark, but Potomac Group had the proper tools to help light the way.
My total time interviewing was probably about two hours, and they are very flexible to your schedule.