Pros
Brilliant colleagues, excellent engineering standards, a clear career progression, ample mentorship, challenging and interesting projects, exposure to the bleeding edge of technologies, excellent work-life balance, top-notch code standards, great benefits, delicious food, beautiful work environment. Internal mobility is amazing. If you ever feel like you need a new team or a new challenge, you can transfer at will. Joining Google doesn't mean you join a particular team, it means you're entering a huge community of brilliant people doing exciting things who are eager to have you join them. You'll learn what it looks like when engineering is done right. Stay for more than a few years and recruiters won't be able to get enough of you. "Ex-Googler" carries a lot of weight, and I've seen lots of people leave Google to take on shockingly influential roles at startups and other companies.
Cons
Promotions are extremely demanding. When in doubt, the entire organization defaults to "no," so you'll need to jump through a lot of hoops to get promoted. Promotions are centered around complexity and impact, which tends to discourage simple solutions to important product problems, as well as low-impact but important work like code maintenance. There have been some attempts to encourage more code maintenance but in my opinion it isn't being rewarded enough. As a result, there is a number of roles that people take on that you tend not to see, most notably that of the code style stickler whose impact comes in the form of improving existing code. Also on the topic of impact, you can execute a large, multi-year project and still not get promoted if it doesn't land with the expected impact. -- This depends on personal preference, but the office spaces are almost universally open-plan, which some people find makes it difficult to focus. Google NYC has been in a real estate crunch for over four years, and people are being hired faster than we can build office space to accommodate them. Lots of trading floor-style desks. -- Personal projects and side hustles are limited to what doesn't compete with any Google products. In theory it sounds reasonable, but in reality Google has a finger in pretty much every pie, which means you'll have to ask permission for everything you make outside work.