Pros
Everyone is really nice and friendly. Information sharing is encouraged and if you're struggling with something, you're urged to ask others to help you. The company doesn't shy away from trying new technologies and lets everyone have their input. Very relaxed atmosphere and flexible hours. No real dress code (unless you're dressed for the beach...). Pizza Fridays are good.
Cons
90% or more of new hires are kids straight out of college. Many of them are smart, but inexperienced. So if you stay at the company for a while, you end up teaching new kids all the time, fixing their mistakes, etc. After a while you may feel like you're teaching introductory programming courses, which gets annoying. Raises are slow to come about. If you start at 50K, it may take you 10 years to get to 100K. The bonuses can be good at the end of the year, but if 50% of your bonus is taken by taxes, you're not left with much.