If you're thinking of getting a new iPhone, at or sometime after, launch day (this Friday), I suggest you do a little research. There is not better place to start than the reviews from various tech sites.
The reviews I recommend you read:
Yahoo! Tech's David Pogue [video review]
Me? I pre-ordered the iPhone 6 Plus. I did my best to try them out with the paper printouts that Apple made available. As these reviews show, it's definitely huge, but I think I'll manage just fine. I was simply too tempted by the better battery life and camera. And that screen looks amazing!