Pros
Work is almost never boring. There's interesting stuff going on if you know where to look for it. Lots of opportunity for career advancement. SpaceX's reputation as a slave driving machine is largely overblown. Company's mission is pretty damn cool, plus you get to work on rockets and spaceships. Subsidized meals make eating pretty cheap. There's lots of options to choose from. The coffee is free and is, in my humble opinion, better than Starbucks.
Cons
Rampant elitism. There are some big egos at this company, and if you clash with them, it's quite unpleasant. This leads to a very noticeable clash between individuals and even departments. Uncle E's strategic vision for the company is largely at odds with the day to day operational demands, which makes day to day life challenging and sometimes stressful. The job could pay more (that's what the _equity_ is for, I suppose).