Pros
In my own experience at my particular contract location the good things were: they had a great relationship with the client so we felt just like a direct-hire, FSA has a great reputation among the clients, most of my coworkers were pleasant and some I consider really great friends, the work (initially at least) is very interesting, very stable, benefits are good, good networking opportunities
Cons
absolutely no room for growth whether it be salary or promotion. The reason is that it is a contract and they can't adjust unless a spot is open up but if they really wanted to, they could pay. I mentioned how I would like more monetary incentives and was told directly that doing so would affect any recommendation to potential future employers. Eventually you get to be great at your job and your job duties won't get more challenging as you are stuck in your contract role. You have to do whatever the client wants, no matter what. Healthcare costs have gone up the past 2 years consecutively by 30% or more.