Once if you buy iPhone, it is not going to be end up with just one time, it is like feeding an elephant. Every month you have to pay for data plan. Find some time, to calculate that data plan for 2 years. Surely it would exceed three hundred dollars per year. Really if that much revenue is getting generated out of that data plan, then undoubtedly it is worth feeding it.
iPad is just bigger size of iTouch, its dimensions also not that much user friendly to carry around. The way iPad was hold, that itself give some idea, how comfortable it would not be. iPhone is having various reasons to justify, no way to deny that. In a single device you can find so many features of the single product like GPS, Camera, iPod, Phone, kindle and etc. iPhone is unbelievably versatile, but same grace is not going to carry forward for their evolution of products.
iTouch = iPhone-phone-camera+WiFi
iPad = magnified (iTouch)
Gullible consumers have to realize, no point in being proud of using costly branded invention of some one. You did not invent anything by your own, so you don’t have to feel great about buying these products. If you find actual use of it, you can go for it, else buy apples with that cost, because an apple a day keeps the doctor away.