Pros
I really enjoy working with my colleagues. Everyone is smart, friendly, and driven. It seems like there is a lot of autonomy here - very little micromanagement, if any. With that being said, everyone works hard and celebrates each others success. The founders are easily accessible and makes it a point to keep the team in the loops with the direction of the company. You have the standard foosball/ping pong table and catered lunch that's offered once a week. Kitchen stocked with goodies. Multiple rooms with couches to work on when you're tired from sitting/standing at your desk. BART is also a short walk away from the building.
Cons
As with most start-ups, the environment is very fast paced. There isn't a lot of hand holding, so you need to be pro-active about finding ways to get things done. The on-boarding process could have been more clearly defined, but nonetheless, it was exciting. You can always find someone to answer your questions. The team is growing significantly, so space is starting to get a bit tight. However, we're in the process of finding additional space.