Well the answer is there are so many features of Google+. But the most important to consider that the features similar to those of other social networking sites such as Facebook and LinkedIn. The way Google+ displays notifications, unread notifications, and links to posts is also similar to Facebook Notifications.
Now, let's see the main features...
1. Circles
Although other users can view a list of people in a user's collection of circles, they cannot view the names of those circles. The privacy settings also allows users to hide the users in their circles as well as who has them in their circle.
Organization is done through a drag-and-drop interface. This system replaces the typical friends list function used by sites such as Facebook.
2. Huddle
"Huddle" is a feature available to Android, iPhone, and SMS devices for communicating through instant messaging within circles.
Texting is great, but not when you're trying to get six different people to decide on a movie. Huddle takes care of it by turning all those different conversations into one simple group chat, so everyone gets on the same page long before thumbs get sore.
3. Hangouts
"Hangouts" are places used to facilitate group video chat (with a maximum of 10 people participating in a single Hangout at any point of time). However, anyone on the web could potentially join the 'Hangout' if they happen to possess the unique URL of the Hangout.
Bumping into friends while you're out and about is one of the best parts of going out and about. With Hangouts, the unplanned meet-up comes to the web for the first time. Let buddies know you're hanging out and see who drops by for a face-to-face-to-face chat. Until they perfect teleportation, it's the next best thing.
4. Instant Upload
"Instant Upload" is specific to Android mobile devices; it stores photos or video in a private album for sharing later.
Taking photos is fun. Sharing photos is fun. Getting photos off your phone and on to the web is pretty much the opposite of fun. With Instant Upload, your photos and videos upload themselves automatically, to a private album on Google+. All you have to do is decide who to share them with.
5. Sparks
"Sparks" is a front-end to Google Search, enabling user to identify topics they might be interested in sharing with others; "featured interests" sparks are also available, based on topics others globally are finding interesting.
A feed of only the things that you're really into, so when you're free, there's always something waiting to be watched, read or shared.
6. Streams
"Streams" is the place to have meaningful conversations with the people you care about. It centralizes all the content people have shared with you, as well as the people who are trying to share with you, but who aren't yet in your circles. You might see text posts, pictures, videos, links, or location markers. When you share with people either individually or through a circle, your content will appear in their stream.
Through "Streams," users see updates from those in their circles, updates similar to Facebook's news feed. The input box allows users to enter a status update or use icons to upload and share photo and videos.
You have seen post about "What Are Features of Google+?", maybe in the next posts I'll give details for each features. Stay tune!
seems cool. can't wait for final release