Not to be a totally jerk, I don't like apple in general b/c they like to overprice everything, but the Iphone isn't a good product in my mind (sorry apple fanboys no disrespect), since number one it doesn't support flash, and two it's not really the easiest thing to open and install a better battery.
BUT I'll give it props on how durable the screen is
2. You don't need a better battery because it's already got a good battery and good battery life at that. I got a friend with an EVO and that giant Seidio battery pack and my phone still lasts longer than his between charges.