Pros
You'll work with some of the smartest, most capable engineers in the world on products that have large audiences. If you're close to research, you'll be doing cutting edge work that gets used. The culture is still about doing great things with integrity. The performance review process strives to ensure egalitarianism. The benefits and infrastructure are outstanding.
Cons
The company is facing a changing public perception and several large legal hurdles, ironic as it's actually very careful with personal data, especially compared with others. It's more of a top-down, large company as it has grown. Working outside of Mountain View can be difficult. Your experience may vary depending on which division you're in, though it's not hard to switch.