About a year ago, Google introduced the Google+ Local App claiming this app was the "most reliable way for iOS users to rate & review on iPhones/iPads/iPod touches." Well no longer!
Abby D from Google announced in the Google Maps Help forum that this app is being shut down on August 7th and being replaced by the Google Maps for Mobile app.
We’re announcing that the Google+ Local app for iOS will be retired on August 7, 2013. This means that, after August 7th, you’ll no longer be able to access the Google+ Local app through your iOS device. Any reviews and ratings that you created will be available on your Google+ profile and in the Google Maps iOS app.
So this app lasted about 12-13 months and now is no longer - consolidation.
Forum discussion at Google Maps Help.