Pros
I joined TDI pretty early on and spent about seven years watching the company grow and make a real difference to our clients. Management all the way up to the CEO is really approachable, and the whole company feels like family more than just a place to work. Your input is appreciated, and when a contract ends and you pass a client's offices on an idle weekend you look at it and say you've personally made a difference there. And speaking of contracts ending, I haven't once feared that TDI wouldn't put me on something new when a contract ended. If you want to and you carry your weight, you'll have a home and career forever.
Cons
I hate moving, and TDI did so three times while I was there. Of course it was always to move into bigger and better office space, but still. But in all seriousness, I can't really think of anything negative, and certainly not of anything that would be unique to TDI.