Good place to build both yourself and your career, most direct supervisors were a delight to work with.
Pros
I worked as a contractor at a federal agency, under a LM contract, for six years. LM bought out the old company, so I had two choices; go with LM or change careers. I took a gamble and it paid off, I stayed with LM. Leadership would often listen to a well-reasoned business case or suggestion, and the tuition assistance program is very nice. In addition, leadership did remove two middle managers who were dishonest, but this did take two years. This cleared the deck for the rest of us to do our jobs, and win three successive contract annual renewals. Further, the company instituted raises tied to your evaluations. It is pleasant to get a slightly larger annual raise because you deliver good work.
Cons
LM is still a very large organization, and therefore does not always rapidly respond to changing market and client requirements. Also, do not expect a rapid solution from Human Resources, you have to be persistent and document every communication with HR to accomplish something. Beats working for a mom&pop company, though.