Pros
Overall, in many ways like Google at ~2004-2005 - but, fortunately, more relaxed. There is enough "green field" work, though less than 16 months ago when I joined. People are pretty energetic and motivated, but, fortunately, not up to the point of being aggressive or creating hierarchical cults. The overall culture is still in many ways engineer-driven. There is free food (very good) and even free beer :) Vacation policy is more or less "get as much as you need, provided it's ok with your manager". There is a free shuttle to the Bay Area... and, oh, yes - the IPO worked very well for employees, as far as I can tell.
Cons
It's difficult to find high-quality engineers and especially managers these days. I feel like the two managers added recently to my extended group are not extremely technically sharp. Also, I feel like occasionally the management in different parts of the company is unable to make a firm decision in one area or another, and lets things drag on their own for too long.