Pros
Having been at Google longer than 9 out of 10 employees, I still feel the business poses me with fresh challenges and terrific learning opportunities virtually every day. I have been able to pursue several distinct "mini-careers" at the company, with promotions and transfers available as I hit major project milestones. The career environment is ideal for someone who thrives on complexity, who takes initiative, and who communicates well and constantly with technical collaborators. I feel that management empowers and facilitates individual contributors. You have a fantastic liberty here to challenge how things are done (whether bureaucratically, technically or in product design). Expect fast and constant change. You can step up and drive that change, too, if you have the chops -- the courage to express a coherent vision, and the stamina and depth of skill to follow through. A high impact project at Google can affect a global user base of hundreds of millions (or is it billions now?), and can shape the course and direction of whole industries. You can provide great benefit to users worldwide. The right answer to a search query can literally save a life, reorient a career, or enrich a relationship. And while search is critically important, we do so much more. When it works, it is a total jazz. When it doesn't work, well, you fail fast and try something new. Everyone outside tends to ask, "What company will be the next Google?", but internally we remain quite ambitious: "My project at Google will be the next Google!" The people here are great to work with. Passionate about ideas, compassionate toward others, with many innovative superstars, and a culture that celebrates diversity. Of course, there is some politics, human nature and fallibility -- as you will find anywhere -- but I find the overall environment positive and well intentioned.
Cons
Working at Google has a stiff learning curve, and it can be challenging to ramp up and get your footing here -- especially if you have been doing software development 10+ years elsewhere and are accustomed to being a big fish. In you aren't on a very short list of luminaries (e.g. a Vint Cerf), then respect and influence have to be re-earned from scratch based on what you do at the company. Your past merits may have helped you get in the door, but inside they buy you nothing. So, to thrive here you have to grow and sustain some inspiration about what's possible, to keep your head above the daily grind of routine work. Working at Google can isolate you from the global technology community, as well as sometimes from our users. We have our own technology stack and internal lingo, so systems and methods learned here aren't always transferable. We exist in an extreme media spotlight, in highly competitive markets, dealing with sensitive information, so we are very cautious about sharing anything externally. The culture tends to be inward facing: everything is on campus (the Googleplex) -- meals, entertainment, perk, education, tech talks -- so why engage outside of the bubble? Our approach is to solve everything with automation so that the system works on a global scale, but human-to-human customer service does not "scale", and so is sometimes given short shrift.