Pros
International business exposure is a plus. Also, many positions at Amex often have daily Interactions with many parts of the company including GCO, Sales/Marketing, Risk Management, Sourcing, CISO and Finance to name a few. You'll get a good understanding of how a business operates from A to Z. Generally speaking, the workforce is polite and people try to get along although the work environment can be very passive at times.
Cons
This used to be a stellar company to work for 4 years ago. Yes, the pay wasn't great but the back end compensation balanced it out if you worked there for at least two years. Bonuses, restricted stock and retirement contributions on top of the standard 401k match really helped out. The medical benefits were a lot better then as well. Now, this company is a shell of its former self-- more like "Meet the Spartans" than "300." A comedy of errors has been played out under current leadership which sent the stock price into the abyss. With the degradation of the back end compensation and decrease in medical benefits, the fact that pay is low is now very underscored.