Pros
The perks and salary are very competitive, you are able to afford a high standard of life for the country you're in, go on lavish vacations, and have a nice business casual wardrobe. The rest depends on the team you are in. Some people are genuinely kind, smart and friendly, some teams genuinely work well together, but overall it is a stressful and competitive environment, which affects people's dynamics in adverse ways.
Cons
While Google staff is made up of many interesting individual personalities, you often get the feeling that you need to think, feel, and breathe Google culture. Your individuality basically gets subsumed into this giant business machine, and good luck to you if your opinions, tastes, and interests don't match the corporate culture. Basically, you need to be into the following things: yoga, inspirational quotes, American left-wing liberalism, going to the gym, new techie gadgets, office fashion, blockbusters, Netflix, travelling, bragging about your accomplishments, money. You need not be into the following things: literature, art, academic pursuits, creative writing, alternative viewpoints, having friends outsie of work, aspiring to anything other than middle management at a huge corporation. All your time with your work friends - the only friends you'll have time to make and keep - will be spent conversing about metrics, meetings with your boss, and how best to make yourself look good for your next performance review. Your mind will be filled with these things all day long, don't kid yourself that you can have brain space for anything else if you want that promotion (and you will, just to get ahead of your office plankton job). The open plan workspace is hugely distracting and exhausting for anyone trying to do some quality work, yet is sold as "teambuilding" (in reality, it is simply the cheapest way to house 1000s of employees)