The polished edge is a matter of grit. Coarse waterstones are anything but polished. The finishing stones produce a polish like a strop but leave the edge profile crisper than a strop.
I think they are not easier to maintain but rather harder to maintain because they need to be flattened way, way more often than oil stones. Flattening them, however, is less time consuming because they wear faster.
Are Shaptons better? Well, some of them are better from my perspective. The reason is that the abrasive in some models is in synthetic matrix as opposed to a clay matrix which most waterstones use. They don't absorb much water so there isn't any need to soak them. You can just wet them and use them. I think they cut a little more slowly than clay matrixed stones but certainly don't wear as fast. I use Shaptons myself but there are plusses and minuses.
Having said that, I gave up oil stones years ago in favor of water stones. Faster is better for me.