Pros
The culture is very special here. Everybody is very focused and vibrant; ideas are cherished and given the opportunity to grow. Everybody is held to a great standard, I honestly feel it keeps everybody's egos in check. Nobody worries about positions or titles, if you work hard you really will be recognized for it. I personally love having a new challenge every day. Like any startup, policies can change overnight, but the more flexible people will not be fazed by it. Very awesome, cutting-edge environment combined with an open office plan makes it a comfortable work environment. Pretty awesome focus on health. Great health insurance plan and benefits, in-office yoga on Fridays, catered (and healthy) lunches every day. Catering company does a great job of making sure everybody's dietary needs are sufficiently met.
Cons
Expectations can be high, but they are manageable and focused without going over the top. For people that prefer a rigid operating and office structure and don't like a very fluid environment, this might not be a good fit. For people that are flexible and curious, this will not be an issue.