Are you guys talking about jailbroken vs non-jailbroken with respect to iPhone's features? Because they are night and day. I have customized the living shit out of my iPhone, and there are quite literally hundreds, maybe thousands of programs, tweaks, utilities, games, apps, skins, boot logos and possibilities for individual customization that are ONLY available for jailbroken iPhones.
I would certainly admit that a non-jailbroken iPhone is going to get it's ass kicked by the other smartphones, but a jailbroken iPhone is a beautiful thing. My brother does a lot of custom stuff and he has made some really cool stuff for my phone like a hippo slider bar (I love hippopotomi), customs carrier logos and all sorts of other stuff he's put together with photoshop.
Also as far as jailbreaking voiding warranty, while they may be true, all you have to do is restore your iPhone and there is no evidence your phone was ever jailbroken (unless Apple wanted to pursue some very deep avenues, which they don't).