Looking at the images and the docs, the colour comes from a filter layer over the display. This matches with the lower colour resolution quoted. I was not impressed with any of eInk's colour technology to this date and I suspect the R1 is going to be equally disappointing.
Looking at the images on
Reinkstone's site, the colour looks very similar to Kaleido2.
Looking at the
good-display.com website, it does say 4096 colours again matching Kaleido.
For the weight, I might as well buy an iPad Air for the 70 grams difference and get a display capable of full colour video at decent frame rates.