Pros
* First, I feel I should comment on the work/life balance. I almost chose not to accept an offer at SpaceX because of the horror stories I'd read on Glassdoor about SpaceX grinding people's personal lives away. In the end, I chose to give it a try and quit in a few months if it was wrecking my life. I figured it was worth the risk, and I'm very glad I decided to try it.
I've been at SpaceX almost two years now, and I have yet to experience (or witness) a major work/life balance problem. Most people in the Redmond office arrive around 9am and leave around 6pm. Most people (in software) in Hawthorne arrive around 10:30am and leave around 7pm. Everyone I know in the office is very clear that they will not do perma-crunch. Many people have families and just can't do it.
Do crunches happen, and do we expect them when we're nearing completion of something? Absolutely, I've seen, and I expect crunches for short periods of time.
Is it a culture of heroics, sacrifice, and permanent crunch mode and stress? Not that I've seen.
If there were huge deadlines that were causing too much pressure for me to be happy in my personal life, do I feel I could set boundaries without jeopardizing my job (or respect inside the company)? Yes.
* I love working in a place where everyone so strongly believes in what they're doing. I think it's a given that SpaceX will pay some amount less to a rockstar than they could make elsewhere (I don't know how much less, maybe 20%), but IMO it's worth the price of admission to get into some of the coolest and most impactful work on Earth. I see so many talented developers working on ad optimization, Tinder clones, boring middleware, etc. One could do that, or one could directly impact cutting-edge technology that take humans to the stars. Because pretty much everyone at SpaceX has consciously made this tradeoff, the company is full of some of the most down-to-Earth, curious, intelligent, and motivated people in the world. I've spent years in companies where people were making tons of money, stuffed to the gills, but they didn't really feel challenged or care much about what they were working on. They were only there for the money, and it was so lame and depressing.
* Every day, I feel like I'm living in a sci-fi novel. There's so much cool technology here, and it feels like we're ushering in the future.
* The work culture is generally professional and respectful
* At the same time, things move quickly and meetings are informal and efficient. Disagreements tend to get resolved quickly, directly, and respectfully.
* I'm constantly learning
* There is freedom to branch out and take on whatever I want to (as long as I take care of prior commitments)
Cons
There's a lot of invention happening at SpaceX, and it can be stressful when there are tight deadlines and you can't estimate how long something will take very well. I've learned that communicating your progress clearly to your manager, VP, etc is very important so everyone can react early if you're getting behind.