Vantaggi
I have been at Amazon for ~6 months as an MLE. Pay is great - there was a pretty clear going rate when I was applying and Amazon came in significantly above this. The interview process was fairly brutal (final interview was 6 hrs!) but the flipside of this is that once you are in you get a lot of trust and support. They seem committed to helping you succeed, and no one is looking over your shoulder or micro managing. I work remotely and have as much freedom to set my work schedule as I did when working at a smaller company. My managers feel like they are there to facilitate my work rather than policing it.
Svantaggi
The biggest con I can think of right now is that the scale of the company makes it feel like it's a bit out of my hands if the decision is made to cut staff from a certain team. I'm not sure how much personal influence I have on overall staffing decisions that directly affect me. But this may be true of any larger company. My attitude is that I'm enjoying the ride for however long it lasts, and if I deliver quality work and show that I can be flexible there should be other opportunities within the company even if there is a change in strategic direction.