I didn't have a 2G, but I liked the look of the 2G. When I held the 2G at the Apple Store, It wasn't as comfortable to hold as the 3G is, though. I would have liked to the 3G to have retained the aluminum, but use the same shape that the 3G currently has.
The aluminum didn't scratch as easily as the plastic on the 3G does. I just got my 3G 3 weeks ago, and it has been in a case since then (except when I clean the phone twice a day), and it still has gotten scratched.
So I would have liked the 3G to be Aluminum but with the curved back.
Don