You can read details about Google’s policies and principles here http://www.google.com/intl/en/policies/
Google in most of the cases is more explicit and open about their changes as well as great at providing tools to download our own data (data liberation) and move on. This openness gets them into trouble and this policy change is no exception.
One of the concern raised was data is shared across many of google’s product to enhance and personalize functionality of that product. Personally we don’t see what’s the big deal here. If we use multiple products from a single company it is quite natural data is shared between them to provide a seamless experience.
For e.g., let’s say you are hosting a event and inviting your friends or family to it. You could create a Event on Google Calendar and invite your friends by adding their email. They get the option to Accept the event and you get notified by email. Think for a second how hard it would be if you can’t share data between gmail and google calendar? You have to do everything manually with total disconnection.
Another example could be manually adding your gmail friends to your circles in Google+.
If still concerned, one work around could be creating different google accounts for various products that you are concerned about.
Please submit this survey/poll as well as share your thoughts through comments below.