Web version, at least. A few thoughts after a very brief spin:
1. The look resembles the Android client. A lot. Rounded plus / comment / share controls. Opening up the post as the full window(ish) to do reading and comments. Rotating comment blurbs. I don't know that I care for it, but I'm sure I'll get used to it.
2. "Events" is missing. This is almost certainly a feature that has to be rolled in to the new interface. Hopefully soon. (Meanwhile, still accessible form the old interface.)
3. On my laptop, things have gone from three-column to two-column; albeit slightly wider columns / larger photos, it's still more white space creep.
4. Harkening back to the first point, to fully read a post, or to read the comments, or to comment, you have to click on the post and have it pull up a full window. That makes visually glancing at other posts not possible, it's slower, and I'm not sure it's actually more functional or efficient.
(Also, when creating a post, the underlying window cannot be scrolled, again making cross-references to other posts that much more difficult.)
5. The share button now is … well, a share button, not just for G+ but also for FB and Twitter. Looks to be using the same code as shows up in Google Photos.
Overall, it appears to be mostly an interface / design tweak, not something that adds actual functionality. The goal is to emphasize use of Communities and Collections; it's not clear how this does that, but I'm sure there's more to it than I've seen in 15 minutes of playing around. (I haven't even scratched into the Collections and Communities interface, just the home stream, but that's where I spend 99% of my time.)
I will say that it's a positive thing that such a significant change has been done, in terms of how it reflects on Google's continued commitment to the product.
Originally shared by +Luke Wroblewski:
Dive into the new Google+
As +Eddie Kessler shared this afternoon (http://goo.gl/2QjBGx), we’ve spent lots of time talking to people who are passionate about Google+. We visited them in their homes, we invited them into early testing communities and we learned more about how and why they use Google+. The predominant answer? Having a great place to keep up with and talk about their interests. From Astrophotography (goo.gl/HRQmIh) to Wild Hummingbirds (https://goo.gl/6FscI6), people are not only discovering amazing things, but meeting others who share their passions as well.
Today we’re taking a big step toward making Google+ an even better place for your interests. To do so, we’ve drastically simplified nearly every aspect of the product. You’ll see this clearly in our new navigation centered around Collections and Communities. Collections let you immerse yourself in content about topics like surfing (https://goo.gl/vvv5QD) or tiny tilt-shift photography scenes (goo.gl/nWyicL) . Communities enable groups of people with the same interests to join up and geek out on anything from Game of Thrones (goo.gl/aaqtgq) to Painting (goo.gl/kmlM7m). With Collections and Communities, discovering amazing things is simple: just follow or join whatever happens to pique your interests.
But we didn’t stop with Collections and Communities; the new Google+ also makes it easier to post, search, connect, and keep up with great content in a fully redesigned home stream. And we’ve worked hard to make our new web experience load fast and work beautifully on devices of all sizes.
You can preview the new Google+ on the web today by signing in and clicking “Let’s go” when you see the prompt. (And since not every feature of Google+ has made its way into this new design, for now, you can toggle back to the classic Google+ with one click in the bottom left-hand corner.) In the coming days, we’ll roll out updated apps for Android and iOS.
While this is an exciting new beginning for us, we’re definitely not done yet. We got here by listening and learning, and will continue doing so. Please visit our Help Center (https://goo.gl/gWsFeh) or drop us a line in our support community (https://goo.gl/eMFVj) to share your thoughts, questions, and more.

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