Pros
The culture - Google has an amazing culture and is a very engineering centric organization. They pretty much defined how the modern silicon valley company should look like and they still do it very well. The learning opportunities - It's possible to move easily between teams at Google and you can learn a lot of about a lot of things. The perks - Everyone's heard of the perks, and they are awesome. The food is great, the benefits are great, the salaries are competitive with bonuses and stock options.
Cons
Sometimes difficult to get recognition for a job well done. Can be a little hectic on some teams, while it can be painfully slow on others. Moving from one team to another hinges on getting well known, and in some instances promoted, yet the promotion process is quite difficult to make it work for you. You may try to get promoted one year and get refused by a committee when another one would have given you the promotion, because the members of that committee were more aware of what you did or who you are.