Pros
This company will push you in a way that reveals your shortcomings as an engineer within the first few weeks, and will show you how to improve your abilities. There is no hand-holding; once you know where you need to improve, the expectation is that you put in the time and effort to make the necessary adjustments. If you are looking to become a more effective engineer, produce some of the best work of your career, and have the motivation to put in the time to get there - this is the place for you.
Cons
If you aren't willing to make the time commitment as an investment in your engineering skills, don't apply for this position. If you are not invested in SpaceX's objectives as a company, you will quickly lose the passion and motivation needed to meet their deadlines and work demands. The adjustment period can be difficult, as you are expected to get up to speed quickly. The structure of the company is very flat and not well defined and communication standards needs some work.