Now, Google + has mainly 5 core features along with many others namely, Circles, Sparks, Hangouts, Instant Upload and Huddle. Ok, so one at a time.
Circles: This is basically, organizing your contacts into groups. Contacts from your GMail will pop up and you can just drag and drop. Doing so, will help better sharing of right info with the right people. It kinda feels like Google has emphasized on this feature of Google +. Something like a stand out feature which of course, exists in Facebook and other social platforms, but may not be so intuitive and fun to use.
Sparks: It's the “sharing engine”. “Great content leads to great conversations,” Vic Gundotra told TechCrunch. So that sums it up. The user searches for a topic over Google and Sparks lets him see real time results, blog posts about it and then add it to to the interests list to refer to it whenever required.
Hangouts: Google pointed out in the interview with TechCrunch, that not many people use Video chat even though they have all the resources. With Hangouts, you let people in a particular circle know that you're interested in a video chat and then people in the same Circle can have something like a video conference, 10 users at a time.
Instant Upload: This feature mainly saves you the trouble of uploading your photo to the web from your Android device. While you are clicking photos and taking videos, Instant Upload will automatically upload it, so you can have the Circle of your choice be able to see them.
Huddle: This is a group text messaging app which works with Android, iPhone allowing you to send SMS to a particular circle. TechCrunch asked Bradley Horowitz, why Google wouldn't use "Disco", the group messaging app built by Google; the former just got a smile in return.
Then there is the Stream, which is your usual Facebook like News Feeds, which shows what people have shared.
What Google has attempted to do with Google + is, create a whole Google ecosystem, which takes advantage of the fact that if you are a person who cannot make it through the day without making a Google search, uses products like GMail, Picasa, Gtalk, share stuff you like with +1, use an Android phone, then you will most likely use Google Plus as well.