Pros
Very capable colleagues, easy to build a network, benefits are great especially if you have a large family. HR-friendly policies while you are billable. It was also very impressive that the CEO took the time, at orientation on day one, to speak with all the new hires, in person. He does this for as many orientations as he is able to. The stock price has risen a lot recently too.
Cons
When your program assignment ends you get a layoff notice a number of weeks before the role ends (which can be as little as two weeks depending on length of service) then go on unpaid leave for a month. This isn't necessarily a reason to avoid working here, just a warning not to stop your job search when you join Leidos, which also means keeping yourself up to date with the internal opportunities.