Just got my conversion kit today from iphonefixed.co.uk
My rating is 6-7/10. Few issues I had with this kit.
-Screen is off centred, definately noticeable.
-front digitizer is not made of glass, seems like hardened plastic. Compared to my original black iphone 4 parts, the surface is less smooth and less glossy compared to the black digitizer and screen.
-near the home button of the screen a small fraction is jus clear and has no white. This is noticable as it makes the home button look uneven.
-light leaks out of the side with the volume button meaning there is a small gap between the digitizers and the middle bezel.
-also never gave me a case

(guess ill let that slide.)
-Dark border around the lcd bit, meaning the white paint used is not truly opaque.
HOWEVER: the actual screen seems to be a true retina display, image quality is superb,
-the back looks absolutely amazing, I would give the back plate a 10/10.
-Looking at the phone from a distance, it looks truly genuine.
-Phone is FULLY funtional, camera, prox sensor, etcc
With the issues I faced I highly doubt these are OEM parts. No way the factory that makes this would have quality issues like this. But overall the phone does look great. I managed to fool a few people thinking it was a real white iphone. Its only when you inspect the details you realise. I mean I know some of you might consider it nitpicking, but for £179.99 I expect the quality to be just as amazing as the black.