Pros
Planet Labs has a very exciting mission, that if well executed could have a seriously major positive impact on the world. The technology is advanced, R&D opportunities abound, and the people are universally driven by the mission, very talented, and genuinely nice.
Cons
Working at Planet can be stressful - the stakes are very high when launching satellites that by nature cannot be fixed once they've been launched. I've found myself second guessing choices, well after the satellites have been shipped. Planet is growing quite rapidly, so it takes a good bit of flexibility to work there. It can also be difficult working in a situation when it seems like there are 100s of very important things to be done, and the work needs to be prioritized.