Pros
While the Amazon mentality is con for others, it's a huge pro for me. My job is loosely defined and I received no formal training upon arrival. I love that. I had to be self-directed, find my own resources and create a niche in my team. My job can be what I make of it. I define my goals, propose projects, suggest changes to existing projects and choose to meet or exceed expectations. Helicopter bosses are not encouraged but I, as an individual contributor, have to do my part to prove that I can work autonomously. On a daily basis I have to find the data to prove my points before blindly making assumptions, write narratives to support my projects and define (and redefine) my goals. Speaking up with constructive solutions is consistently encouraged. The famous "?" email from Bezos, while intimidating, reminds us that everything is open for questioning and smart inquisition is encouraged. Amazon is the only company I've worked for that loudly and proudly displays its leadership competencies. In fact, almost everything I do can roll up into a particular leadership competency. Usually our actions are justified and rewarded in accordance with these core values. Finally, I love that we're encouraged to change positions every 18-24 months (lateral move or otherwise) so no one gets stuck in a single-minded rut. I had the fortune of being asked to move to a better role after just 6 months (a rare exception).
Cons
Be prepared to work very hard. This isn't a con per se, but you should be mindful of that fact. I have worked 80 hours per week during heavy times and never less than 55 on any week. No one tells me to work this much; you have to figure out how much time it will take you to achieve your goals and do it. Also, don't expect "perks". Again, this isn't a huge con for me. I feel like people who go to work for "perks" aren't sincere. If you need rewards or praise for your work, you may not find it here. Finally, the autonomous mentality means that no one on your team is ever obligated to help you unless their manager tells them to. Help is hard to come by more than once so ask for favors wisely. Compensation is "meh" but opportunities are great. Also, if you stay long enough for all of your stocks to vest (like, minimum of five years), you'll have a nice little package of money eventually.