Pros
Number 1: I have huge respect for the founders. They are dedicated and driven, with a strong vision of where we are going, but they manage to be kind and human as well. Number 2: I love the people I work with. Fun, interesting, honest, and super smart. Number 3: I love the work I do. None of the work I do feels wasted, and the planning and project assignment process is transparent and sensible. Oh, and we have office dogs to play with if I need distraction!
Cons
We move fast; it's a startup. Sometimes keeping up with the vision of the company takes lots of energy. I will say that when things do go wrong (plans get delayed, etc) there is careful analysis of what happened, tweaks are made to the process, and there is no finger pointing!