The integrated group conversation feature ("Huddle") is really slick.
Not as nice on a Honeycomb tablet; you get the typical "just stretch the phone interface" behavior. It's still usable, but just not optimal. Honestly I'm a little surprised they didn't push this app out the door without a tablet-specific interface.
The only "real time" group conversation feature is "Huddle," which is just a group text chat -- and this feature isn't available on the website at all, only on the native mobile app. I've only used this feature once; I might use it more often if I had more friends with Android phones who were also on Google+.
It's pretty nice when people try to get you to remove some pictures (e.g. it's useful for some protesters), since as soon as you get a picture it's on the cloud.
Some googlers said that if you want live chat on google+ desktop, you just post something and the page updates automatically with new comments. Giving the same experience as a group chat, not to mention hangouts which have both chat and video.