it's just aesthetics......the wheel looks cheap on the 4g...that horrible grey color......i really like the click wheel....it's more confortable if you're trying to navigate with one hand.....that's true. But it looks cheaper.
The 3g looks more sophisticated, more APPLE-like with the Red lighting buttons (Play/Stop, |>> <<|, MENU) overall i really like the 3g better.
but like i said to me the 4g would have been the greatest thing in the world if the click wheel would have looked like the buttons on the 3g with the red light and the - WHITE - scroll wheel but in the same possition as in 4g (the four of em around the click-wheel, for easy one-hand use)
i'm just talking about looks, not functionality................'cause of course the 4g's gonna be better.... it's improved........and the battery life and all...........so my opinion is only look-wise.
if my 3g f*cks up of course i'd get a 4g, but....i'm really happy i bought my 3g iPod. (and the irony of it all is that i got my 3g 2 weeks before the 4g introduction, i just didn't know that they were about to release the 4g's so i was in U.S. on vacation and decided to buy it (here in Dominican Republic they're too expensive), and if i'm lucky that i STILL like the 3g better, cause if not i'd have been knocking my head on the table! 😛)