Pros
Excellent exposure to a broad variety of projects, clients, and smart people. Constantly in learning mode as the exposure challenges you, always put outside the comfort zone your skills stay sharp and evolves. If you get in with the right clique, you will get exposed to the best projects. Learn which managers you work with best and just stick with them.
Cons
Highly political place. Reviews process is arcane and illogical. Managers spend time writing descriptions of projects, but the review is done by people who have no logical connection to you. Sure if you know someone in the review process who can bat for you, you will be in better footing but wouldn't it make sense to be reviewed by someone who actually *gasps* works with you!?! Pay is static, the pay you come in at is what you get paid until you get promoted. Vacation time and personal life is non-existent. You will work long hours and travel a ton, and that is expected as a baseline. Some people are highly competitive and will step on you to get ahead. Highly matrixed, difficult to find your place unless you have a helping hand (insider to help you)