I don't know what kind of magic that Google has. Even when they released an app for another platform like iOS, their magic is still too strong. It only takes one day for Google Plus app for ipad, iphone and ipod touch to reach the top of the free app list in the App Store. As there are already more than 10 million people on Google Plus, I can see how they can achieve that rapid success.
However, people may think that Google should do much better than this. The google plus ipad app is still pretty much buggy so that Google release an update to patch the bug in the first day, but the app still frequently crash when you try to look for your stream.
If you haven't try this new social network, it is pretty much the same with Facebook, only with some unique addition. You will be forced to divide your friends into something called Circles so you can share something only with the people on the specific Circles. The mobile version of the site and the google plus ipad app have a few features which will make it useful when you try it. The mobile version will allow you to include location on your updates.