Amazon

Opportunities to work on assignments that have a real impact on the company and drive innovation. You won't be assigned stuff that wouldn't realistically be considered useful to customers. This may include external people or organizations, but also internal teams as well.

It is very sink or swim on your own. You are assigned a mentor, but your mileage will vary. I have had very helpful mentors, but I have also heard from other fellow interns that they don't get any help at all from their mentors.

Amazon's full-time return offers are fungible and very general. The good point of that is you don't have to return to your intern team; you can switch to another team in another organization (i.e., from Kindle to AWS). However, I would prefer allowing interns to lock in their team or location assignment as part of their acceptance of their return offer. Currently, you can only give your team/location preference when you accept, but it isn't guaranteed. You may be surprised after you have already accepted that you have been assigned to a team or place that you didn't want.