Somewhat informal, and I felt very comfortable. I was asked the usual questions (why do you want to work here, etc..). I was told about the working hours and asked if the hours worked for me (day, mid or night shift).

Three people interviewed me and switched back and forth asking about 10-15 questions. It lasted about 20 mins. Since it was for an entry level position the questions were relatively easy and focused on my experience/education and how I would handle certain situations.