Pros
None. This is just a horrible employer where a large part of their business is augmenting the staff of the government with positions nobody wants for long.
Cons
ICF government services business model means they are powerless to improve your client-site situation (even if it's a simple matter of office work-space). All they try to get you to do is believe the lies they push on the client as well as work both ends against the middle. It's a real downward spiral for ICF because they can rarely keep higher-educated people at the government client sites. If you are in government, in some cases all you need is time on the job and a heartbeat to take on management responsibilities (and they love to throw their weight around with contractors). ICF is right behind them. The benefit to you is that you get TWO boneheads to work for! If you like both a day-to-day client bonehead to work for as well as a useless ICF "manager," then this is the place for you.