my iphone is all beat-up. i was planning on getting a new one but waited for the announcement. i have a black 3g. why should i buy a 3gs over just another 3g. the 3g is cheaper. are there any design differences like a matte back? i understand the 3gs is faster, faster doing what? 3g is already fast and at home on wifi my phone is as fast as my macbook pro. I don't care about video. what are the other differences?