Pros
They have an inspiring mission. The people I worked with were ambitious and smart. I learned a lot from my colleagues and I learned a lot on my feet. I got to do a wide range of things that I had no experience with so it was a great training ground.
Cons
The founder is manipulative and disrespectful -- a lion in sheep's clothing. He inserts himself in every aspect of the business (even the minute details). There's no autonomy and he is great at making people feel unsupported and competitive with each other, and it trickles down to every level of the company. Goals change constantly, and generally the approach was unfocused. There was a lot of start and stopping, and unrealistic goals given the lack of resources. Raises are very few and far between, and you have to basically threaten to quit in order to get one.