I worked at Google 2016-2020 as an SRE in Ads. It was ok. It was definitely big corporation in that making globally optimal decisions was mired in bureaucracy and the upper management would say whatever they think would make the company happiest rather than their actual goals (lots of internal "PR" instead of transparency). But I don't think this is actually much different from other large companies, and day to day work was clear and valuable to the company.