Check out the New Sony Xperia Go 2 (Xperia Advance 2 in the US). Gone are the ugly bezel on the bottom, and what we have now is a sleeker, uniform shape. The Xperia Go 2 maintains the same overall dimensions as the Xperia Go. The screen has been bumped from 3.5" to 3.75".
The capacitive home button are gone. It is replaced with a "hard" home button. The Go 2 maintains it's dust proof and waterproof features as the original.
Ram has been upgraded to 1GB whereas the original had 512k.
Here is a comparison of the Xperia Go 2 vs the iPhone 5.
Xperia Go vs Xperia Go 2.