MarkWebb

I think having Apple Pay (and the NFC transponder can probably be used for other tap and pay services as well) on a 4" phone is huge. The way I view phone sizes (although I sometimes change my viewpoint weekly!) is that 4" is ideal for messenger apps (Line, iMessage) and communicating (old fashioned phone call, FaceTime, Skype, Hangouts, Line/Viber/etc. voice and video); 4.7" is better for watching YouTube than 4"; and 5.5" is better for web browsing, since you can migrate, for the first time, from mobile site view to full desktop view (albeit with some eyestrain). 4.7" is the "Goldilocks size" because it's not whompingly bigger than the 4" but still offers 1080p/50fps on YouTube - the smallest iPhone that can handle true 1080p (the 5 series is slightly less than 1080p). It's also more pocketable. For my personal use, I carry a 5s as a phone, but use a Nexus 6p as a portable tablet - powered by Fi, it's very cheap to own a second line.