It's damn good. It actually makes me want to use Google+ just for the hell of it. It looks so elegant. I mean, it's probably the sharpest looking mobile app around, certainly within the social media bunch. And it works very nicely too; none of the annoying lagging in the Facebook mobile app.
If you use Google+ there's no reason not to download this app. Of course, there's no reason to use Google+ but, hey, who am I to tell you what to do?