Google+´s only major call is, that it can easily piggyback on other Google services. For Google, its a logical protective mode from having “social as a platform” as they have been communicating now. We have noticed that if you sign-up on Gmail or YouTube, you basically automatically get a Google+ account created (no wonder a big amount of Google+ users are simply not active, because the registration was “bundled” to them).
But a lot may change now. Google is using its search super-power now to strike back. If you basically search for a brand that is supported on Google, say “YouTube”, it shows you the link to its Google+ page.
Searching for the top Google+ brands on Socialbakers, most of the TOP 50 brands on Google+ dont appear in the enhanced page listings yet, but perhaps its a premium feature that will get activated only for a subset of the pages.
You can see how it works when searching for YouTube, check out how the right top corner promotes its Google+ page!