Gone is the dashboard of icons that once greeted you upon opening Google+ for Android. Now, you can zip around the app with a drop-down navigation ribbon on the left of the screen. This gives you easier access to your Stream, Profile, Messenger, Hangout, Photos, and Circles. As a whole, the app is easy to use and just as intuitive as its desktop counterpart.
Stream Stream is really the lifeblood of Google+. Your primary view will probably be All Circles, but you can also swipe left or right to view other feeds like What's Hot (trending posts on the social network) and Nearby (other Google+ users in your vicinity). Additionally, you can add your own feeds if you want to keep tabs specifically for Family, Co-workers, and so on. As of yet, though, you cannot create a custom feed with more than one circle (Family & Friends, for instance).
Within your Stream, you can do almost everything you can on the full desktop version of Google+. You can easily comment on, share, and +1 items, and, of course, create and edit your own posts with pictures, videos, and location tags. You can even download photos from posts, directly onto your device. As for the way the Stream looks, I'm on the fence. The wide images can look stunning if they're in high-res, but just the same, they can make the interface look messy and cluttered if not (especially with the overlaid headlines and buttons).
Messenger The Messenger feature lets you chat with one or more of your Google+ connections from a single panel. You can even add photos to your conversation, either from your album, or directly from your Android camera. The feature is easy to use and has tons of potential when it comes to coordinating with friends. For instance, it could be a more convenient and powerful alternative to mass-texting, if most of your friends are on Google+, that is.
Hangout With the Google+ app, you can easily create a new Hangout (video call) while on the go. And with a couple of taps, you can enable or disable audio or video, or switch cameras. Also, it's just as easy to join a Hangout in progress, if you come across one in your stream. If someone invites you to a Hangout, your phone will notify, much like it would for a typical voice call, and upon answering, you can decide to enable or disable video. If a lot of your friends are on Google+, then this feature is probably going to be a much simpler option than, say, Skype.
Photos As expected, this is the hub for all of your photos and videos. It provides a simple interface for viewing and commenting on items from your circles, items you're tagged in, and, of course, all of your own album items. Unfortunately, unlike the desktop version of Google+, the app doesn't let you share or add tags to photos. But you can easily download photos or set them as wallpaper.
One thing I love about the Google+ app is that it includes an Instant Upload feature, which automatically backs up pictures and videos taken on your Android device. By default, these items go into the private "From your phone" album, where you can easily access and share them at your convenience. Of course, you can disable Instant Upload if you're worried about battery drain, but I think it's a superconvenient feature that should be utilized.
Profile Here, you can see your Google+ public profile page, all of your posts, and all of your photos. Unfortunately, you cannot edit any of your profile information (except for your photo) from the Google+ app, which is a minor letdown.
Circles This section of the app lets you view and manage all of your Google+ Circles just as you can do on Google+ desktop. You can easily view posts and photos for individual Circles, create new Circles, and move people between Circles. The experience here is very much the same as it is on the desktop.
Overall, the Google+ app provides an excellent way to interface with the Google+ social space while on the go. While it does appear to be missing a few features, I'm confident that Google is on its way to porting them over. Whether you're a regular Google+ user, or you're just interested in the Instant Upload or Hangouts features, you don't want to miss the Google+ app for Android.