Pros
Great place to start a career, you can learn quickly . I think for beginners who want to learn very quickly and are ready to do long working day, go ahead. There are many projects for fortune 500 companies and contrary to what others might say i found it very easy to go from projects to projects (it highly depends on how much you cost to the project). You can have easy access to knowledge and meet some experts. Negotiate well your salary because it's unlikely to be increased.
Cons
Pressure, hard to have a well balanced private life, high turnover. Managers have a very short term view put employees under high pressure to deliver on time. I have worked on projects where everybody on the team left except 1 or 2 guy (including me) because they were completly burned-out. Many pretend to leave because they can earn more in other companies but i am not convinced that's the only reason.