You really need to do some research.
iPad 2 = BIG BATTERY
iPhone 4 = small battery
It's amazing what some people write.
Maybe you could add something like also as simple: Bigger Screen!!!
Also,
If someone had the experience of having an iphone 3G/ 3GS or 4 has the RIGHT to question about the battery .
As what Apple claims isn't the reality.
Charging the device every day. Worry if it's possible to use some application or use the web otherwise the battery just disappears so fast u can't even realize it! Then no phone calls NOTHING.
I've read some reviews of people claiming the same about ipad2... so no surprise there.
Maybe You should try to actually use your apple device and get to know it. Or read a bit more.