Pros
Very fulfulling work, feeling like you are contributing to an important chapter of history. Good cafeteria on site. The ability to walk down to the first floor and talk with shop workers about manufacturing limitations, and see spacecraft being built all around you.
Cons
SpaceX is quickly losing its small-company feel. By now it's unthinkable for the engineers actually to fabricate parts, and production parts are the high priority in the shops (not R&D). The stock options are a joke at this point, and they're bringing in a classroom full of people every week. Don't come here if you're expecting the company SpaceX was 5 years ago. High turnover and burnout rate. Their MO is to hire fresh college graduates, overwork and underpay them for a few years because they don't know any better. There used to be free dinner at 7:30, the CEO emailed the company criticizing those who stayed until 7:30 for the dinner then left, then they just started charging for the dinner. Meager benefits, (notice how many people list "free coffee and frozen yogurt" as 'Pros'? That should illustrate how much one has to stretch. You'll quickly tire of eating frozen yogurt every day, and how much would you be spending on your own coffee? $1.50/day? Wow, awesome 'perk.') Universal condemnation and lack of respect for competitors, even the CEO blatantly jokes about competitors. Blind CEO/COO worship, even a senior manager commented that it's a "Emperor's New Clothes" atmosphere in that no one brings serious glaring issues to the top officials and problems get ignored and swept under the veneer of everything being great, operating nominally, etc. Of course, when you feel you could be fired any given day, why would you? Overall a cult-like atmosphere of superiority, and yet an "us vs. them" childlike clique mentality between groups, lots of blame and finger pointing over delays. Lots of media hype-mongering as well, future projects are touted as if they're fully operational and tested, while problems with real hardware are ignored and hush-hushed. At one point a launch feed video blackout was explained away as "we decided to forego the video feed because launches have become so routine." WHAT?! Boring location; you have to live at least 10 miles away if you want to be anywhere interesting and it takes 15 minutes to get from the parking garage to HQ.