There was one 2 on 1 interview which was behavioral but you have to have technical knowledge to seem competent. The whole process was fairly simple and the fact that they had food while you waited (1+ hour) was nice. It actually snowed while I was there but they helped me get out in time. Overall it was a good experience.

Rigourous, multiple phases and they make sure that you are serious in defense contracting. Also check for your knowledge of certain systems related to the job posting. Do your research on them