I went through four interviews in a row (2 hrs in total) in one day. Interviews were all pretty nice. The first was a HR personnel asking general questions. The second was with an actuary, who asked technical questions. Only one actuary gave technical questions, and they are not not too specific. The rest of the interview were quite open and were general and behavioral questions. The third was with a new actuary still in their student program, and was very casual. The last was with the intern student program's director. She was very nice, and very open to questions. The most important advice is: prepare as many questions as possible, and make sure they are good (at lease with some depth showing understanding/interest of the field)

It was very laid back, nothing too formal. The interviewers asked basic questions about my resume and asked me to explain my accomplishments. They always asked if you had any questions at the end.