I just went to the apple website and from what i can see, the iphone 5 and 4gs seem like the same thing. Its got slight upgrades to retina display and the screens a little bigger, but i didn't think their was anything wrong with 4gs.
Added (1). Other than the headphones, thats the only noticeable upgrade that i can see
Added (2). I kno and i figured they didn't call 4gs 5 was because they were saving 5 for gamechanging technology like making the iphone a wireless hotspot. Its pretty disappointed.seems like their is no significant difference.
Added (3). The bigger screens kinda nice (from 4.5 in. To 4.87)
better Wi-Fi (still not a Wi-Fi hotspot like android is)
better resolution
better map (roadside assistant, i don't know why they didn't have that in the 1st place)