The iPhone 6 is actually 17 grams heavier than the 5S but it feels lighter, due to not being as dense. The glass over the screen is thinner, making taps feel more hollow than on the old phone, or even the iPad. The combination of these things makes the iPhone 6 feel cheaper than the 5S somehow.
I agree with most of Hackett’s review, but this blurb I have to strongly disagree with. To me the fit and finish of the iPhone 6, feel in hand, and ever other detail feels leaps and bounds better than the iPhone 5s. It’s not even close if you ask me. I’m not sure what he means about feeling more hollow, it feels more solid to me. The iPhone 5S always felt kind of empty to me.
The iPhone 6 feels like solid metal and glass.