In summary, Google My Business is the new unified interface designed to make life easier for local businesses as well as brands to be better found within Google.
- Edit the business listing by changing hours, description and so on
- View managers of the page but not manage them
- Post to Google+
- Add photos and update cover and profile photos
- View local insights & analytics
- Change business pages and accounts
For a more detailed walk through of the app, see Mike Blumenthals blog.