Fun environment where you can really flourish. Everyone is really talented and collaborate in a way that I've never encountered before. Like any place there are fun projects and projects that you... just want to get through, but the good stuff is more and more frequent. Plus, the great projects are really career building.
Not much anymore, there was a rocky period in the past, but it's amazing how far we've come since our true "start-up" days. If you don't want to define your own role and instead just wait to be told... everything, it's not for you.