I've currently got a shuffle, 3rd gen nano and a Touch and am firmly of the opinion that they're all fantastic interfaces and form factors
in the right circumstances
The shuffle is perfect for the gym, not just because you don't have to be particularly accurate when changing volume or track but, obviously, the lack of screen and simple, tough buttons makes it practically bomb-proof.
The nano is, by far and away, the best of the three for sticking in a pocket and using on the move. Can navigate it blind, small form factor and light weight are perfect when you're on the move and the capacity is bang on too.
The touch, on the other hand, is simply the best PDA I've ever used. Okay, granted, the choice of apps could be better but the standard stuff is stunning, the touch interface is a joy and using it at home when you can relax and truly appreciate that screen and all it offers is an experience that beats any other portable device I've ever used.
That said, I think I'll always have a click wheel device (or equivalent) if possible. I just prefer it for the daily slog and I don't really see how you'd get the Touch technology in a device the size of a Nano. Plus it's a damn sight cheaper if you loose it and less of my life is contained within for someone to 'borrow'
Basically, different tools for different jobs seems like the way to go. Now if Apple brought out a Touch Nano with a click wheel on the back....
