Problem would be in the day to day use.
You would notice every damn time you need to whip out an SMS reply with a single hand, even though now you don't.
And then your jeans are tight and your all curved up and you feel like you're going to break it.
I wanted to love it but in the end I could never feel comfortable with that phone.
Love my 5, and love especially that its performance hasn't suffered. Still a slick phone. Of course Touch ID and slo-mo camera would be great, but progress can wait. But I'd rather upgrade to a 5s than a 6 or 6+ for the time being.
I'll be a sad panda if they ever completely abandon the 4"