Pros
Great, sharp, smart people - most of whom are willing to be helpful, have energy, work hard and are full of team spirit.
Cons
Back-stabbing, internal politics, very little people manager opportunities, jack-of-all-trades approach means you spend lots of time doing menial and unfulfilling tasks you probably did much earlier in your career. Very poorly defined career paths. The most popular level position is filled with tons and tons of people with a huge range of years of experience. Lack of levels and poorly defined positions/roles. If you are early in your career and join, you will probably like it and be energized by culture and work. If you are coming from years at other companies, beware to feel like you've taken a huge step down in your role / nature of day to day work; may find it demeaning and the lack of structure frustrating.