Pros
There are of course, the tiny perks like free coffee and frozen yogurt, the discounted meals from the on-site cafeterias, and the freedom to walk around on the factory floor and watch an entire rocket be built literally from the ground up. Pay is decent for interns, but living in the LA area is extremely expensive, so that pay mostly disappears for living expenses like rent. From what I heard, salary for full-time employees used to be good when the company was young and stock options were a good sign-up bonus, but now the stock price has basically stagnated so the salary may not be as competitive. But the actual benefits of working here is that you get to see your work make a tremendous impact within only a few months as opposed to a few years with other traditional companies. SpaceX's mission is really inspiring, and HR knows this and uses it to pull the best possible talent pool.
Cons
Work-life balance is non-existent. Sure, no one forces you to stay more than 8 hours every day, but if you only work 40 hours a day, people begin to assume you're not working hard enough and you'll more than likely be fired in a few days. For interns, they make it near impossible for you to work only 8 hours a week, especially if you live in corporate housing. The earliest shuttle that takes interns home leaves at 6:30 PM, so unless you take the last possible shuttle in at 9 AM (which again leads to people usually thinking you're lazy), you'll usually end up working 50 hours a week whether you want to or not. Promotions are meaningless, since everyone is so young that most of management has very little experience with actually leading teams. And the employees that have been around the longest keep trying to manage the company as if it were still a small startup, which is impossible now that the company has grown so large. You're always hearing from upper-management about how "back in the day, we didn't have all these people/resources to get the job done, and we still got it done better!" But putting all that aside, the worst part is that HR doesn't really do a good job of vetting interns and new hires selected by teams. When teams or management interview potential candidates, they hardly pay attention to the hiring process. During my interview, it felt like the team members there were more concerned about making it to their next meeting in time than evaluating my skills and interests. Because of this, oftentimes people quit or are fired after only a few years because they burn out so quickly. Unless you absolutely are in love with your job and career and care about it more than anything else in your life, you will eventually begin to burn out and hate working here.