The only thing I don't like about the new G+ Photos app is that the share menu is inconsistent from every other single application and paradigm in Android. Which is OK if they plan on making it the standard going forward, but it sticks out now.
Oh and the folder structure for local files still seems a bit weird to me, but not in a way that hampers the use of the app.
I've chosen to always open it instead of Gallery whenever presented with the option, just to be prepared for the switchover. Thinking of outright disabling the gallery too, although, that might mess with the camera... hmm. That's probably why they didn't remove Gallery in KitKat, the integration with the Camera app isn't there yet (swiping to the right to view photos, etc.)