Yes, I was in the EE shop yesterday and compared the XR straight out of the box to the XS. The difference between OLED and LCD was night and day when placed next to each other. By itself, the XR screen looked lovely however when you see the XS, the XS whites were whiter than white whereas the XR was more beige yellow. I showed the girl and said to her, 'Can you see the difference between OLED and old fashioned LCD?'.
Here in the UK, the XR is only £10 to £15 per month cheaper than the XS on a contract. Personally, I'd rather pay the extra and go for the XS and for me, it's a nicer size. The XR was way too big for my taste and i'm not a fan of aluminium.