Finally got around to installing the latest version of Gallery 3 to replace the older Gallery 2. Links to the old gallery should redirect to the new one, but I haven't had a chance to rigorously test it yet.
Everything is still OOtB (out of the box) Gallery so it looks pretty vanilla. I'll see what neat new themes I can put up to make it look pretty. So far everything seems to work ok, although importing the photos from Gallery 2 turned out to be kind of a slow process.
So far I'm liking the new version of Gallery. Some of the tasks that were a bit of a chore in 2.x are a lot easier now in 3.x.