Pros
Perhaps the most exciting company to work for in the world at the moment given what we are doing and the pace of change things happen - definitely never a dull day in the office. SpaceX has very little red tape and enables its employees to really make an impact. Especially if you are coming right out of school and want to work on real projects, SpaceX will throw you right into the deep end. You get to work with tons of incredibly smart and motivated people every day. Creates a great environment for learning new things and pushing yourself to achieve your potential.
Cons
Work/life balance is still an issue at SpaceX, but I will say that in my 3 years working this issue has gotten much better. When I first started 60+ hr weeks were the norm across the board, but now I'd say the vast majority of people are no longer working that much. That being said 50-55 hrs a week is standard and I don't think anyone is working less than 50 hrs. Also, if you have your sights set on moving up the ladder, you need to be one of the people in the 60+ hrs a week camp, effectively making you choose between career advancement and having a life outside work.