When it comes to privacy, Google's rep isn't necessarily leaps and bounds ahead of Facebook's, but Google+ has truly been designed to put the user in charge. The service gives you all sorts of granular controls over who can see what on the site. Because your contacts have been arranged in to groups, it's easy to tell Google+ who to share your information with and who not to.
The site goes the extra mile by giving you authorization rights to photo tags before they're made public and by letting you determine which friends show up on your profile as a member of your circles. If you want, you can keep the members of your circles hidden from the public entirely, and people you add to circles never know what circle you put them in.
When you make a post on Google+, not only do you decide if everyone or only certain people can see it, but it's easy to do things like turning off comments or disabling re-posting elsewhere. And if you ever decide to leave the social network, you can download all of the data you've put on the site and take it with you.