Here are a few screen shots that I've captured on my iPhone to show you. It works exactly the same on Android devices. I have to say that Google has done a great job with their mobile dev. This is way beyond what Facebook has been able to do.
This is the homepage of sort. Nothing ground-breaking here.
This is the stream page where you can write updates and share them with which ever circle you wish.
This is the circles page. This manipulation for sharing your stream updates with specific people is very easy. You can't do this easily on Facebook so expect Facebook to copy this. Hey it is how the industry works sometimes.
This is the profile page. It's like the stream page except this page allows you to focus one specific individual in your circle.
Again, Google has come a long long way since their mobile search and email pages. With the Plus effort, Google has leaped over everyone and showed just what can be done to create a Webapp if you are willing to innovate.
With Plus, Google has take a huge swipe at Facebook and blurred the line between native and Web-based apps.