It sure sounds scary, but when I actually try to think about what it is actually bad about it, I can't really think of any.
Every single user Google got, they signed up voluntarily. Google never forced anyone to sign up for their services.
Google attempts to learn about its users just like every other companies. It's just that Google does it so much better than others. Do you get the label "corporate mass surveillance", when the company becomes so good learning about its users?