I used the towel last night on my old DD, a white 1994 Volvo 940 turbo. The hood looked MUCH better afterwards, and the process a LOT quicker than clay. I saw a bit of marring on the front trailing edge afterwards, but I'm not sure if that was already there. It came out with some vigorous rubbing with a foam pad and Meguiar's cleaner carnauba wax.
One thing I noticed is that the cloth needs a very liberal amount of the lubricant solution on it. Maybe the marring happened on spots that I didn't wet down enough. Also, it did a fantastic job of removing rail dust-- the Meguiar's clay I used barely removed it, but the cloth removed it really quickly. Judging by that, the cloth seems to be more aggressive than clay, so plan on using lots of surface lubricant, apply gentle pressure, and of course follow up with a wax/sealant.
That's my .02