The Nano clearomizer/cartomizer is filled simply by removing the mouthpiece. Most of the ce3 devices require a fine needle and syringe to be inserted into a tiny hole in the top of the ce3. So the Nano is much simpler to fill.
Right, im not too concerned about the filling process though. I'm patient and they include a syringe with the CE3's. I'm more concerned with leakage issues and easiness of cleaning. Any thoughts on those two factors?