Pros
Working at Dropbox was the best decision I ever made. I was a little wary before I interviewed, concerned that it might be just another hot tech company with inflated egos and over-the-top perks. Thankfully, these concerns were extremely far from the truth. I adore my team members -- they are incredibly talented, humble, passionate, hardworking, collaborative, and just generally good people. The flat organizational structure means no one thinks twice about pitching in on something where their expertise is needed, and it also means that opportunities to get involved across a variety of different projects are yours for the taking. The company is maniacally focused on doing the right thing for users, and on making beautifully simple products that genuinely make people's lives easier. So refreshing and motivating. And of course, there are the perks :) The food is AMAZING, the gym and massages are awesome, etc. It really is the most incredible place to work.
Cons
There are definitely some growing pains; we've been growing so quickly that we've had to hack some solutions together. Now we need more established processes.