Pros
While I worked for Amex (2010-2015) I had full benefits, plenty of vacation & sick time, and very good pay. The direct leaders were generally pleasant and nice to deal with. Unfortunately upper management screwed it all up.
Cons
They will lay people off at the drop of a hat. Not just people, but entire departments. Feels like a slap in the face when the company literally says "We would rather pay someone in India or the Philippines $8 an hour than pay you a decent wage". Also, like other reviewers have stated, the environment can get a bit toxic. Not in a "there's alt-right trolls up in here", but more of a "management makes incompetent decisions that makes everyone feel nervous/uneasy". While I was there, one of my co-workers pointed out to management that the monthly performance goals seemed to be shifting based on employee performance. What this means is that management would look at the previous month's results and shift the monthly goals based on that. This would create scenarios where "low performing employees" who were trying to make an effort to improve their stats (harder than it sounds) would still be considered "low performance" and be fired with no severance or benefits. Overall it was not a happy experience.