For one thing, while you're making edits, you can move between images and the system will save any changes. When you're ready, you just have to hit "Done" or "Revert to Original" if you decide not to keep the tweaks. There's also a new aspect ratio selector that lets you crop exactly to the original size, square, 4:3 or 16:9. So far, the tweaks haven't appeared in the Photos smartphone apps, but it seems like a no-brainer that they'll arrive there soon.