Critics, however, say combining all the user data from your various Google accounts has another big effect: Google gets to assemble a very detailed dossier on you–including some bits of information that you might prefer to keep private. As the Electronic Frontier Foundation explains, "search data can reveal particularly sensitive information about you, including facts about your location, interests, age, sexual orientation, religion, health concerns, and more."
As Nick Mediati writes on PC World, "this grand consolidation means that all of your Google account data will live in a single database that every Google service can access. Google Maps will have access to your Gmail data, which will have access to your YouTube history, and so on."
So. Can you simply opt out? No, you can't. As one writer put it, "you can accept, or decline and be banished."
"Google’s new privacy announcement is frustrating and a little frightening,” Common Sense Media chief executive James Steyer told The Washington Post. “Even if the company believes that tracking users across all platforms improves their services, consumers should still have the option to opt out — especially the kids and teens who are avid users of YouTube, Gmail and Google Search.”
The EFF recommends people with Google accounts disable their web history. (You can get step-by-step directions to do that here) It won't keep Google from collecting and keeping information about you, but it will limit what Google does with that information, including having your info "partially anonymized after 18 months."
PC World's Mediaiti describes another way of protecting yourself from Google's new all-in policy, which he calls "the nuclear option." Essentially, you delete all your Google accounts. You lose everything, though it's not entirely clear what Google gets rid of when you hit "delete." What is clear is that the company will no longer complile new information about you.