I went through it decades ago, but I have seen it from the hiring side when selecting summer hires. The most annoying part is that the NSA does not communicate during the interview process--the applicant is left uninformed of his or her status most of the time. The second most annoying part is the polygraph.

thorough and friendly. It is a bit lengthy, but the questions they ask are reasonable. There are 3 sections with breaks in between. The pace is very well kept. I highly recommend applying for any math positions offered there.