Pros
Do you want to work with ridiculously smart and hard working people? Do you want to build the world's most innovative space vehicles? Do you want to take part in crucial milestones that will make humanity a space-faring race? Do you want to move at a superhuman pace doing ridiculously cool things? Do you want to accelerate your career at least twice the speed? Do you want a much bigger job scope than what you have now, with a lot more engaging work? Do you want to nix having a job description, and take ownership for any and every problem without concerns of stepping on people's toes or fighting resistance to change? Do you want experience in what it takes to run a company at it's most basic level, when there isn't a system or process, or the system or process isn't good enough to work well? And then fix the system or process? Do you want to get away from a job doing nothing but plugging numbers into something like SAP, and take responsibility for way bigger things that you should probably have responsibility for at this point in your career?
Cons
Are you willing to live in a sketchy area, with roommates? Are you willing to work at all hours as the norm, and have little time for life? Are you willing to spend time in traffic everywhere you go? Are you willing to fight really hard to make friends in a city where people fear making friends (aka Hollywood culture)? Are you willing to live in a city with progressive social norms, where churches are small and rare, taxes will take an extra 15% of your income, parking is not free, and everything costs more? Are you willing to work within the Elon culture, which is not fun like other tech companies? He pushes for the sake of pushing, and the culture is aggressive and impersonal. Are you willing to work with no support from management, or maybe managers that make things less clear/more difficult? Your manager may be your age and amazing technically, but have no clue how to lead or manage. Are you willing to never get a promotion unless you work longer than anybody else? Everyone at SpaceX is ridiculously smart and hard working.