Apple say that the iPhone 3G S is up to twice as fast as the iPhone 3G, and that in turn was twice as fast as the original iPhone. So, if you still have the original model, then it's probably worth trading up for the speed increase alone.
Apple iPhone 3G S On the back is a three megapixel camera with autofocus, but no flash. The iPhone 3G S is the first iPhone to include video recording (something that other phones have had for years). Apple say that the 3G S can record up to 640 x 480 pixels at 30 frames per second, which is comparable with most other high-end phones. It doesn't really compete with the 5, 8 or even 12 megapixel cameras in some rivals though, but it is certainly a huge improvement over the old model.