You might already know that if you only choose the anonymous data sharing option, Google will remove all identifiable information about your website, so you are safe.

They will combine that data with hundreds of other anonymous sites in similar industries and report them in an aggregate form.

The good thing about this is that only users who have opted to share their site's data with Google may use these new or improved services. Learn more about this here

There is an interesting article about why some people prefer not to go all the way with that on TechCrunch