
App is free and available from the Android Market but you can't use it until you have got the Google+ invitation from someone. GUI of the app looks great and it is very easy to use. You'll get 5 icons on the home screen: Stream, Huddle, Photos, Profile and Circles. Stream is equivalent to a wall post conversation in Facebook, like a group discussion. Huddle is a private conversation with some individual or circle.
In Photos sections you can browse through yours as well as your friend's shared pics. If you have integrated Picasa to Google+ then you can also see your Picasa albums in this section.
Circles are like groups of your friends. Although there are four default circles availabe, you can also add new circles. In the pic there are 6 circles with the number of members. Circles are special addition in social networking zone. Earlier we had to think before we posted any content on our Facebook wall because our friend list contained many family members, colleagues with bosses, professors etc. That problem has been solved by circles, you can chose which content to share with which circle.
Clicking on Profile icon just shows your profile, if you want to see you friends profile you can go Circle and search for the friend and click on the "About" tab at the bottom.
Notifications can be seen on the Notification bar, there are a few options to change the notifications when you click on the settings button of the phone. Additionally there is one "Instant Upload settings" link too, which gives detailed settings for uploads.
There is still lot to improve in the app, we can imagine of integration of many other Google services e.g Google Music, Latitude, Youtube, Blogger, Gtalk etc.
Android app has a couple of features missing which you can get on the web (Desktop Browser e.g. Chrome) for example Sparks, Chat and Hangout. A full review of Google+ can be found here:
http://www.geekistry.com/2011/06/30/google-plus-smells-like-google-looks-like-facebook-tastes-like-apple/
and here: http://www.engadget.com/2011/06/28/google-invite-received-we-go-hands-on/
