Pros
This company is pushing the boundaries of what the human race can achieve - that by itself should be driving you to work for SpaceX. All interns are given meaningful projects that have tremendous impact on the business. A lot of the mundane things are done by the full-time employees to give the interns a chance to drive real change. Many of the changes proposed by interns are actually implemented by the company. Free froyo everyday. Amazing food. You get to watch the launch from mission control.
Cons
A little confusing in terms of work place expectations, and since SpaceX is still considered a start up, things will be confusing. There's a lot to learn and it's impossible to understand everything you need to know during training. You really have to pay attention to details and force yourself to digest how everything around you functions.