If this is true, it would be a very poor choice of dimensions IMO - far too thin.
You cannot keep increasing the length of the phone without increasing it's width too, as the phone starts to lose proportion.
The ratio is already bad enough on the iPhone 5 which is too long for its width and if (as it looks from this photo), the phone isn't getting any wider, adding yet more length onto the phone would be ridiculous.
So bigger is better, but it means bigger in both length and width otherwise bigger is just silly!
The picture is of a 5s. It's the same proportion.