Pros
You build rockets. You make history. SpaceX is one of the most high profile companies that you can work for, and there is nothing cooler than seeing all the progress that you make being talked about around the world. Saying that you're surrounded by smart people is an understatement. You are constantly challenged to be the best that you can be, and you will always have to be innovating to keep up. I've learned so much in such a short amount of time it's amazing to think that I've only been here for a few months.
Cons
Three year anniversaries are treated like 30 year anniversaries. Highly intense work comes at the cost of high employee turnover. Prospects of moving up are also very low. You will most likely be stuck in your current job unless there is a shakeup or your superior leaves.