Pros
Excellent benefits especially while you are traveling. Many folks pocket their per diem and you can take personal vacations for the rest of your life with all the points and miles you earn from your hotel stays and flights.
Cons
Managers and above think they can control you by threatening your performance review which you get after finishing your role on every project. This intimidation is used to make you do things you ordinarily would not have to do, like skip a wedding to fly into the client's site early. Also you may get stuck in a city you dont like for months while working on a project or be relocated to an international office to complete an international project with less than 24 hour notice (you can say no, but there is always pressure to remain staffed on a project).