Pluses: Nice opportunities for growth and learning, the ability to work with big name clients, good work life balance, even if you are salaries, some levels get paid overtime, benefits are decent (Stock Purchase Plan, 401K company contributions), paid time off based on years of service performed.
Cons: After a role ends, must go on something similar to another whole job search to find a new role. Sometimes you are put on roles which may not be your specialization. Work can be dreary, mundane. Managers can be dumb. I was promoted at mid-year, but the base pay increase was very minimal.