I've been using G+ since before it became public, and it has since gone through two major UI revisions. Personally, I really like the newest UI (released yesterday), though I wasn't as shocked as most because the new G+ looks an awful lot like another social network I'd been toying with for the last few weeks called Kumbuya.
Be that as it may, I find that the new UI is clean with lots of white pace, and configurable. My only beef is the new Hangouts panel on the right. When it was Chat it used to sort the list by online up top, away/busy in the meddle, and offline down at the bottom. Now it shows 10 random contacts, and only 3 of these contacts are actually in my circles; the other 7 are random Gmail contacts. I can also find no way to manipulate this list. I call this an out of box fail.
I'd like to hear thoughts from other Google+ users. If you don't use it, fine, but please don't troll the comments about how you think G+ is lame, etc. I love it, and as far as I'm concerned it stands head and shoulders above Farcebook.