Pros
The advantage of working for a large, stable company while each division is like a small company. The work is project-based, so each year or two you get to start something from the ground up. If one part of the business is down for a while, usually other parts are doing well. There is great deal of allowance for shaping a project, and new ideas that improve it are usually accepted. The company is highly dynamic - if there is a new market, and if there is a business case to pursue it, you can do so. If you like to travel, Bechtel is the place to be. Employees you work with are from many countries of the world - you get a global perspective. I cannot recall a project or job I did not like.
Cons
Corporate functions can tend to become bureaucratic. Projects start and they end - you need to be looking out for what the next project you can work on. It is possible to live in one place for a long time, but you need to be flexible in what you do. The bottom line is -- well -- the bottom line. Being able to compete on cost is very important, so if this is not your cup of tea, then this is not your company.