Great for Engineers, tricky for Product people
Pros
extremely smart co-workers, a lot of resources, excellent perks and working environment, modern internal tools, an innovative and smart environment. if you have an opportunity to work there, there's really little reason not to try it for a few years at least. if you thrive, you thrive, if you don't, it looks great on the resume. one of Google's main attractions as an employer is that it's really a win-win to work there.
Cons
overall Google's focus is on defending their cash cow; their other activities almost seem like they're just trying to keep talent off the market and away from competitors. that means if you're an engineer, you'll have a great time. but if you're a product-oriented person, caring about market success, customer satisfaction, etc, you'll get frustrated after a few years. top management is very split in it's priorities, there are generally a lot of chefs involved in any decision making, and the decisions tend to be reversed or altered fairly quickly. a surprisingly large percentage of the senior talent do not view Google as a long-term career path, which leads them to focus on a couple of promotion phases and then they're off somewhere else.