I thought that too, but recently went into a Verizon store and played with the iphone 6+ since the specs are the same. Now, I really couldn't truly hand it free-form, because it was attached by this security knob on the back to a cord to a table, but it was pretty darned close to holding it naturally. And, I really didn't feel overwhelmed by it. I probably couldn't do the swipe-down from the top one-handed, or at least I could have to shift it in my hand a bit, but the rest of the screen could be reached by my thumb one-handed. Now, that was without a case on it of course....
This is really frustrating, as several other first-impression reviewers have said good things about the screen brightness of the 5x outdoors, and one even said it was more legible than the 6p! Sigh...Glad I haven't canceled the 6p order yet.