Pros
There are a lot of interesting projects and teams at Amazon, and there is a lot of opportunity to work on things that you care about. It's very team dependent though, as each team has its own personality and work culture. There's a lot of opportunities for you to own your project and make it succeed. Your team also encourages you to ask questions often so that you can excel on your project and learn more about the company. Work-life balance was decent, and there weren't too many times I had to stay insanely late in the office. Again, this will be team dependent, and a few of my friends had to work extremely late to finish their project. There are also intern events throughout the summer, though not as elaborate as the ones from Microsoft or Google. You're in charge of finding your own friendships and groups as well.
Kontras
As there are many different diverse teams, it can be hit and miss whether you get placed on a team that you mesh well with or get matched up with a project that you enjoy. I felt I was placed on a friendly team, yet I felt I didn't receive much guidance from them. At times it may be difficult to figure out where to get information you need for your project. It's possible to implement something yet find out later that it was the wrong approach due to only one-two people on your team knowing how that system works, but they're out sick or on vacation. Everyone values the leadership principles, especially ones like "bias for action." It's up to you to take charge of your project and your career, and it can feel intimidating at times, as you may not know what to work on next or how to improve. It's something that they don't directly tell you, so you may end up struggling if you're not sure where to go next. For example, managers may not always schedule one on ones with you; you need to go schedule them yourself and really push yourself out there to get feedback, especially if the managers are very busy.