Pros
DOJ is a generally friendly atmosphere, with a lot of opportunities to meet other people your age if you're a paralegal. Work is generally stress-free, particularly if you are on a laid back team or division. Pay is on a GS scale so you will earn the same amount whether you are working your tail off or simply lazing around. Work schedule is very fluid, so many people either work out during lunch breaks or take breaks whenever they please.
Cons
Work is unbearably dull, and this is not made evident in the interview or job description. Expect little to no variety in your days as a paralegal, and don't think that document review will be a small portion of your experience. Ever since I started all I have done is review documents with no change. There is absolutely no accountability in the system, and communication between members of the department is nonexistent. Without having clear expectations the majority of people either put a marginal effort into what they're working on, or none at all. It is not unusual to spend an entire day at your desk without seeing, talking, or interacting with another person. Trial is the most exciting time, but trials rarely happen. Unless you are planning on attending law school, and need to have this experience on your resume I would highly suggest not taking this job.