Pros
Google is an extraordinary place to work: the perks are second to none, the quality of employees is exceptionally high, and the products are mostly cutting edge and interesting. Google treats its employees very well and believes in leadership from the bottom up, which provides a sense of ownership and personal investment that is unequaled in my experience. Google employees are encouraged to treat each other as respected equals, no matter what the difference in job title might be. Google also encourages the notion that good ideas can come from anywhere, and that the best ideas rarely come from management. Perhaps most importantly, Google is one of the only places in the world where you can work on products that could potentially be used by hundreds of millions of people. It's very satisfying to share your work with family and friends, and to see people using your products nearly every day.
Cons
The larger the company gets, the more the culture becomes dilute. The past year or two has brought extensive change in terms of management hierarchy to certain area of the company. With the hiring or more and more managers from the outside, the company has lost some of its democratic idealism in favor of traditional corporate politics. Google is now a very large company, and it's hard to avoid all of the downsides that accompany such size. It can also be very difficult to find a career path at Google. Promotions are exceptionally rare. Despite the fact that employees can theoretically excel in both individual contributor and management tracks, there is still a feeling that the only way to climb the corporate ladder is to become a manager. It's also the case that people are often promoted into management roles without the necessary skills and training, leading to poor relationships between teams and leaders. It also becomes more and more difficult to make fast progress on projects as the company gets larger. Google is still very nimble compared to most large companies, but it's no longer a scrappy startup unencumbered by size.