Pros
If you like to be constantly challenged, aren't intimidated by intelligent people or hard work, than SpaceX is the place to work. Yes, it's fast pace and yes, we can work long hours - but it's typically peaks and valleys. We don't work long hours because someone is making us. We work long hours because the work is fun and addicting. You will not be rewarded because you work long hours. You'll get rewarded because you are productive - don't get distracted by squirrels and you'll be fine. Side perk: working for SpaceX is generally a great conversation topic when meeting new people.
Cons
The company is very design engineering focused and so if you aren't a rocket designer you can be made to feel like you're less important. But I remind myself (and others) that my group supports the business systems which supports the making of the rockets which generates the cash flow needed to get to Mars.