Pros
The people you will be working with are amazingly clever. The "bar raising" approach they bring to interviews really has done a lot to keep the employee base competent. You will be building software used my hundreds of thousands of people.
Cons
My only real problem with Amazon was the massive time drain and how it ate into my personal life outside of "work hours"; 60-70 hour weeks were the norm. The team I was on owned a very high profile though and others didn't seem to have this problem. I suspect that this was a perfect storm of my own tendency toward working a lot, a manager that always wanted more, and the company culture -- maybe if you are a bit better at separating work and life or the team you're interviewing with is a bit more slack you won't have the same burn out I did. Just a note: I lived across the lake which meant an additional 1.5 hours each day on the bus. While it is more expensive in the city it's probably worth it in the end. After Amazon was done with me those hours on the bus were pretty valuable.