Pros
SpaceX is a great chance to participate in a historic and, potentially, world-changing program My coworkers are dedicated and energetic, ready to help out and work late in order to solve problems and make sure important jobs are not neglected. My workplace is sci-fi chic, with a top notch cafeteria, free espresso beverages, and decorated with museum-worthy pieces of hardware, including a flown Dragon spacecraft and a flown Falcon 9 rocket stage. My work is rewarding, in that I can make a meaningful contribution to the program while also learning a lot about my own and many other disciplines.
Cons
The successful employee must accept uncertainty and ambiguity. Much of my work requires having a flexible schedule, because tests and launches are often delayed. Shared tools are constantly "improving", which means adding features I don't understand while removing features I really like.