Pros
The Food! Lots of events happening on a daily basis that allow you to disconnect from work. A younger demographic that's great for singles or folks who like to make close friends with their coworkers. You can come up with and run with any ideas you think are worthwhile. Not a huge amount of red tape to change process. Very easy to get international exposure because of Google's large reach across the globe.
Cons
You get spoiled with all of the food and perks etc. There are a lot of folks in management that have excellent academic records but very little experience when it comes to actual business strategy or people management. This can hurt if you're looking to find a mentor with some real experience. Also, it's hard to get rewarded for simply being stellar at your core job. Reward is given to those who simply come up with projects for the sake of coming up with projects, which isn't necessarily best for Google or it's employees.