Pros
The ideas behind the company - collaboration, smart people, work-life balance - are all good. There are lots of great co-workers there and nice perks like concierge service and inviting office space. They talk a lot about maintaining company culture and have employee events throughout the year. Benefits are very competitive for a company this size, and salaries are not the highest, but still fair. Offer an annual employee bonus based on company profitability.
Cons
If you are in the good graces of senior management, it's fine. But once it's been decided that you made a mistake, or "don't fit", it's best to get out fast. Opportunities are often based on favorites, not ability. The emphasis on in-office interactions means that regular teleworking is generally frowned upon, except for certain situations or people. And each part of the company is really different from the other in terms of opportunities, workload, and interactions - some places are better than others.