Interns have always been a part of the SAS culture. It makes sense - SAS originated while Jim Goodnight, founder and CEO of SAS, was a professor at NC State University.
Before anything else you need to be dependable and collaborative. Success comes from people working well together creating a team where the total is greater than the sum of the parts.
So what is it like? It is one of the most exhilarating challenging difficult frustrating and ultimately rewarding jobs you will ever have. If you like it, you'll find yourself unable to go work anywhere else. If you don't like the environment, then it'll be painfully awful.