If you are in a dilemma on whether to buy the iPhone 4 when it launches on the 30th July (that is this week). Maybe this video will help. 4 generation of iPhones (iPhone 2G, iPhone 3G, iPhone 3Gs, iPhone 4) placed side by side and performing the same tasks. I guess you already know the winner but it is still fun to watch.
If you look at those iPhones, they looks basically the same. Same screen size and the familar one button on the front. If you can disregards the antenna issue, the iPhone 4 is definitely the winner.