Amazing company culture, products, technology, and employee benefits.
Pros
The best part about working at Google is the number of very smart people constantly around you. Great team settings where you can learn and be around the best. There are tons of other employee benefits as well, such as the free food (3 meals a day cooked by excellent chefs) and snacks, game areas (fooseball, volleyball), bicycles, workout center, laundry machines, etc. All of these things cause you to worry about less outside of work.
Cons
Because of the large amounts of benefits (such as free foods) there seems to be an unsaid rule that employees are expected to work longer hours. Many people work more than 8 hours a day and then will be on email or work for a couple hours at home, at night as well (or on the weekends). It may be hard to perform extremely well with a good work/life balance.