Something about iOS on the iPad makes its shortcomings more tolerable. The larger screen just allows for more functionality in Mail, Safari, the keyboard, etc. For example, tabs with Safari on the iPad is close to tabs on a computer; you just click the tab you want (still hate that you can only open 9 though). Whereas Safari on the iPhone requires to hit the tab button, swipe, then pick the tab you want. Things like gestures too, like pinching to get back to the home screen, or swiping left/right to quickly switch between apps, or sliding up to see the list of opened apps, etc. also help make the experience much more fluid and intuitive versus how things are done with the iPhone.