Pros
Opportunity to work on unique, state-of-the-art projects. There will be periods of time when there is little to do but you can always self-study for more certs. There are always opportunities to collaborate with other people and to learn new things. There will be times when travelling that you will need to work long hours....but the work is 'big' and important and you will have no problem doing so. The company will pay for additional training if you are there long enough. It is really dependent on what type of manager you have. I didn't receive permission for training, but a couple of guys who quit after attending boot camps to get Cisco CCNP were paid for training.
Cons
Managers who won't approve travel expenses till several weeks after the trip. Managers who will only approve FAA pay (upfront expenses for 30 days) till after the 30 days are up. Some project managers are extreme at micro-managing. Very poor at communicating what is happening. Plan on not knowing if you are going to travel till the day before. Plan on explaining every expense. For gas purchases while on the road, you don't need to submit a copy of the receipt. However, when entering that info into expense form...you must type a note explaining what, where, when, and why. Lets see...American Express says it is gas purchased at Exxon in Atlanta. So your note would read. While working on the such and such project in Atlanta, Georgia, my car was running low on gasoline and I had to purchase more. For purchase of food at lunch...there would be a receipt for 9.00 at Richie's Deli....so your explanation would read....on jan 3, 2009, I ate lunch at Richie's Deli in Atlanta, Georgia while working on such and such project for GDIT. I think you get the picture.