I bought a M.F. protector for my lady's iPod nano (I bought her a pink one from Colorware and the MF protector for comparison to mine. I have to say I wasn't overly fond of it. It did not stick well, but BIG DISCLAIMER I am pretty sure that this was due to the surface of the custom nano not being flat. The paint becomes slightly raised around the edges (by the clickwheel etc.) and so the surface isn't perfectly flat (just how the paint goes on). THUS I imagine that with a flat surface it sticks perfectly. After all many people recommend them. That said, they did look to be a little too 'easy-remove'. The invisible shield is very sticky when set (you have to apply it properly by moistening the adhesive).

I was surprised at the stiffness of the MF protector -somewhere between a credit card and a sheet of OHP plastic. The Invisible Shield one is a lot more malleable. I can't honestly say what it would be like for long-term stylus use, but I also imagine the I.S. protector would be a lot more pleasant to use than the M.F. one. The best analogy I can come up with is writing on a sheet of paper with a few sheets of paper underneath (invis shield) or a sheet of paper placed on a hard surface (MF).