This was a summer internship with the iPod New Tech group at Apple that evaluates vendor technologies for iPods
Pros
You get to work with ridiculously intelligent people who are also very creative. Keep in mind that the engineers who make Apple products are also the users and they control their entire hardware/software stack, which is very enabling on a company level. Apple is also a great place to learn about designing products for user benefit, which is not always apparent in other organizations - designing an experience is of the utmost importance and part of the culture of the company.
Cons
One of the hardest parts of working at Apple is how busy everyone is and how hard it can be to get time and resources from people. A lot of times you have to be very inventive and maybe take a less efficient route if it means not involving other teams that don't have the time to spend on your project. I imagine this gets easier as you advance in rank, but as an intern it can be hard. You could also look at that as an opportunity for growth. The other hard part of working there is not having a lot of freedom to actually take your products to market and test them out - there is a lot of filtration of ideas that occurs, even before Steve Jobs can slam an idea.