Pros
Pay is, or was, decent for new grads. Intern programs will get you plenty of training and experience in multiple offices quickly, so you don't have to worry about being stuck somewhere that's not a good fit. If you're in Maryland, reasonable access to internal training. The usual federal government advantages apply: reasonable vacation time (4 wks/yr after 3 yr service), extremely low expense ratio for retirement account, job security (barring furloughs). Oh, and doing SIGINT is fun.
Cons
Major caveat: if you don't get hired into an intern (development) program, do not accept the offer. You'll be on a two-year probationary period, during which you can't apply for internal vacancies, so development programs are the only way to make sure you aren't stuck in a bad office. NSA is extremely headquarters-centric; HR processes work on the assumption that you'll go back to Maryland in a few years. As a result, it's difficult to apply to the jobs you want if you're not at headquarters, because you'd have to curtail your tour and that takes lots of paperwork. (Staying in one place generally doesn't seem to be a problem if you really want to, however.) This may not be a problem if you like the DC area, but if you don't then it does limit your options. Sadly, the agency doesn't care about professional development like it used to. Between the fallout from the GSA affair and leadership's desire to do who-knows-what with the money, good luck getting to any external conferences. NSA seems to have a fetish for open-plan architecture to a disastrous degree.