On one level, the with the rest of the Google-verse is a benefit for the social network. But, on another level it is sort of creepy and difficult to manage.
Once you join Google+, it is instantaneously ubiquitous. Go to Gmail, and there it is--that '+Tony' at the upper left on the menu of links with the other Google services. Go to Documents, there it is again. Go to Photos, and...well, it's there, but now it says '+You' instead of '+Tony'. Go to Calendar, and...well, it's not there--but, you get the idea.
Click on your name at the upper right of any of the Google services to open the drop-down box for things like Account Settings, and you will notice a new entry on the menu--Circles. As you might expect, clicking it takes you to the Google+ Circles page where you can create and manage circles and drag and drop contacts into various circles. Interestingly, the drop-down box from Google Calendar does not have the Circles option. Apparently, Google+ is just not integrated with Calendar (yet).
One thing you can do with Circles is add users who aren't even on Google+. You can add Google account email addresses to a Google+ Circle, and when you post an update for that circle, the individual will get a notification email with a link to join Google+. However, it gets a little weird when you are on the Google+ page.
Google+ 'borrows' liberally from the in terms of the basic layout. On the right pane, Facebook will suggest other Facebook users you may know so you can connect with them. I am not sure of the algorithm used--whether it suggests based on who went to your same school, or who works at your same company, or some sort of association based on how many of your existing connections are already 'Friends' with the contact. I do know this, though; the people it suggests are Facebook users who already have Facebook accounts.
Not so with Google+. Google+ will suggest other Google+ users you may know, but Google+ has also woven its way into my Google Contacts, or Gmail, or something, and most of the suggestions it makes are for me to add users who don't even have Google+ accounts. Based on the process outlined above, this is a great system for Google to be able to propagate Google+ and lure new members in, but it may confuse people who don't understand why the people they added to their circles aren't engaging, and it seems more than a little sneaky.
There are benefits to having the social network integrated with other areas of our lives. But, with other social networks, those integrations are a conscious choice made on a case by case basis. With Google+, your entire Google ecosystem is integrated whether you like it or not.
Google gives you an option to delete your Google+ content, or even your entire Google Profile (not to be confused with your Google Account). Google is honest and up front, though, about the fact that doing so may be tricky. The text at the top says, "If you delete Google+, Google attempts to restore your experience of other Google products to the way it was before you joined Google+, and to permanently delete your Google+ circles, posts, and comments."
Note the key word "attempts". It comes up again if you choose to delete your Google Profile instead of just the Google+ content. "Over the next few days, Google will attempt to delete your Google profile and the features and the data that depend on it."
Google+ has privacy controls to enable you to manage how and where data is shared, but with Google+ tied in to every aspect of your Google account, understanding and maintaining the various interactions . If Google isn't even sure it can eradicate your Google+ info, what chance do average users have of keeping track of it all?