The app also includes an initial menu page, enabling quick access to the key Google+ screens (stream, menu, photos, events, circles) and you can also return to this menu page, with a quick back button press (though the mobile site has its own menu functionality).
Because of the way the Google Plus Viewer has been implemented there is a bug that means you may need to re-enter your log-in information from time to tome (the browser control element does not allow full control over cookies and sessions). Having everything sitting in a browser control component does have some limitations; there are some performance issues (notably when loading the control on lower specification devices) and, of course, it doesn't really fit in with the feel of Metro.
As such it's probably fair to describe Google Plus Viewer as a clever work around app, rather than a full client app. However, until Google release a full set of APIs for the service, or modify their browser detection code to give Windows Phone access to the "full" mobile site, then this is probably the best solution for those looking to use and interact with Google+ on a Windows Phone device.
Marketplace description:
Browse Google+ on your Windows Phone with Google Plus Viewer. Keeping the same visual style of the Android application, Google Plus Viewer is actually the best way to browse Google+ on the Marketplace. More features will be added once Google will have release the APIs.
Google Plus Viewer can be downloaded from the Windows Phone Marketplace. The app costs £0.79 / $0.99 / €0.99; no trial is available.