Pros
Very cool work. If your looking for a more fulfilling career SpaceX will help with that. It seems like every person that works here is SpaceX fanatic. SpaceX is quick to make adjustments when something is found (process changes for efficiency). Free snacks and drinks (lunches aren't free anymore, but are $3 for a hot meal). I don't feel that pay is all that bad, it is comparable to other aerospace companies. SpaceX has a fair amount of observed holidays (if you work a holiday salaried you get credited PTO). PTO is accrued per pay period (will end up at about 15 days off accrued per year). Sick time is separate and accrues at a lesser rate then vacation time. You get awesome deals on stuff from the SpaceX store.
Cons
People seem to lack the ability to relax, like they are about to be fired at all times. No 401k matching, but there are stock options if your salaried. Health insurance is pretty good (if you pick the lowest levels you don't have to contribute for insurance) dental/vision too. Engineering jobs are salaried, techs are hourly in general. You will work hard here, when there are upcoming goals you can expect 80+ hour weeks. People do have a difficulty with detaching work life and personal life.