Pros
The biggest 'Pro' about SpaceX is its overall mission and the goals it is working towards. You will work with some very dedicated people on projects that most will think are impossible, and continue to dig deep and find what you and your team are capable of. It also looks great on a resume, and for those who care what others think, it sounds great to the outside world when you tell them that you work here.
Cons
SpaceX will work you into the ground for little to no reward. The company claims to be merit based, which is a joke. Over the last few years, it has moved from a company that strived to make the impossible happen, with dedicated people that all pulled their weight, to teams of looters who are more SpaceX fanboys than actual boots on the ground, make it happen type people. You will spend months of your life on the road with zero appreciation or compensation, other than threats to keep your job. Also, anticipate a very hostile work environment, with management continuously looking for a scape goat to pin issues on. Be prepared to be belittled and threatened to keep your mouth shut on issues as well. My favorite quote I got from management on a very large project during reviews was "Well upper management doesn't know you were the one who made this project come to fruition and did all the work, thats why you didn't anything for it" If you are not part of the "boys club", do not anticipate a promotion or bonuses of any sort (no matter how many fires you put out). Do not anticipate a career path; it does not exist here. Managements idea of a career path is "Here, have another project to keep you busy"