For isntance, take iBooks. On the 3G, iBooks was just not working at all. It was so freaking slow, there was no use in having the app. Take the iPhone 4, however, and you get major improvements, but sometimes it lags. For example, if you switch to landscape mode, it takes a while to actually do the switch on the screen and then if you go back to the iphone being vertical it takes a few seconds to realize you've switched. Anyone else notice this?