Pros
The people you work with are the best part about SpaceX. All people at all levels (senior managers, leads, engineers, technicians, etc) are very smart and very motivated. The pace of development is extremely fast which keeps things exciting. Lots of autonomy, never have been micromanaged, people are empowered to make their own decisions for the good of the company. You get to work on the coolest rockets and spacecraft ever made. Generally well-compensated for hard work and going above and beyond (although this definitely varies between groups)
Cons
Extreme work hours and demand to be “on call” 24/7. There is no escape from work. This is classic spacex and part of the reason why the company works so fast, but leads to burnout and the legendary high turnover. Most groups are chronically understaffed which causes constant chaos and problems which are only solved by working unsustainable hours.