i bought it and tried it,2 words , shoe polish,cuz thats all it is.
Bought a kit for my Lightstone seats, the drivers seat had the usual dark cracking marks. The kit comprised of two bottles, one was a dye and the other a sealer. A couple of coats covered the dark cracks and it looks fine after 12 months. The colour was a good match too. I think the name of the stuff was Liptone or similar. The option is to lash out £1000+ on a reupholstery job from someone like Nationwide in Redditch.