Pros
Nothing - I still have nightmares about working for AMEX. So a pro could be NOT working for them anymore.
Cons
This company is comprised of a bunch of crooks. I am honestly shocked they still exist. Any government contract they are awarded is a waste of taxpayer dollars. They consistently lied, cheated, and treated their project staff poorly. They changed the employee handbook without telling employees so they could change the rules to get employees in trouble when they weren't operating within the new, mysterious rules. They lost PII (personal identifiable information - like SSNs) documents. Bullied staff - staff always felt like they were going to be fired. Had an incompetent clown of a project manager who treated staff like children and made us 'repeat after him' like we were in 2nd grade. Very low pay and no opportunity to negotiate. They let our insurance expire without telling us - so there was a period of time we weren't insured. The messed with leave balances. These are the most unprofessional group of people I have ever worked with. Do yourself a favor and run away from Amex as fast as you can.