They have fantastic pay for the position you're in, and they teach you interesting and engaging utility of modern technology mixed with legacy fundamentals. I've learned quite a bit while AmEx while getting paid more than fairly - I'd recommend a stretch here to whomever may be reading this!
Desventajas
The Company is huge, and at times it may take more than a little time to get recognized for your abilities and the growth you've had. There's a reason there is a "only way up is out" reputation exists for some enterprise companies...