Pros
The best reasons to work at Google are: 1) You want to make a difference in the world, 2) You love a fast paced environment, 3) You love technology, and would kill to be one of the first to see and play with it. Yes, the perks are great but at the end of the day if your work impacts billions of people in a positive way, it all pays for any of the free gourmet lunches. Work at Google and be the envy of all your Friends.
Cons
Google is BIG! As much as they do not like admitting it, "There are POLITICS at Google" Much of how Google runs is based on favors or who you know. Also, there IS a developing Hierarchy at Google between the Project Managers and everybody else. Elitism is not an uncommon trait of Googlers who joined Google right out of college.