He states £159 is a bit of a stretch, also actually already wants to get a Moto G.
But damn I don't want to be branded a fanboy...
Spend £650 and get an iPhone 5S. By far the best use of your money considering the OP clearly isn't really interested in smart phones has he has made do with a flip up for years.
Get a Moto G or a Nexus 5, why? They are both amazing value for money, well built and well supported on the software side. Android is by far and away the most rounded mobile OS out there. No fanboy here, I personally hate my Nexus 5, the camera is rubbish and the speakers aren't as good as my HTC One, but they can be had for sub £300 now. The Snapdragon 800 absolutely flies. I've never used a Moto G myself but it's a cheap phone running android, no reason it wont be good?
Ignore Brenn47, he's clearly mental.