I had an iphone 3g and recently got a 4s. My thoughts on the iphone 4s form factor is that it is - Not ergonomic to hold as the 3g. The 3g had a curved back which kind of fits into the palm of the hand and thus more ergonomic. - Glass back doesnt make sense Who looks at the back of the phone anyway? Having glass on the back of the phone makes it heavier and more fragile. Many people use a case which covers the back and even if you dont, most times, u look at the screen in front. Overall, I much prefer the form factor of the 3g/3gs as opposed to the 4/4s.