I just got my iPhone 4 replaced at a genius bar because it's home button was sticking sometimes. It was the original one I had gotten when I pre-ordered and then received actually the day before the official launch. Therefore, mine was produced before Apple started selling them and had any feed back. This replacement refurbished phone, which the genius claims is essentially new, does seem snappier and music plays louder. That might just be from the fresh battery So I guess my question is, have there been any notable improvements made to the black GSM iPhone 4 since it was released in June 2010?