I find that odd, seeing as the fiddling I've done with both the content aware tools and the resynth GIMP tool has been very effective and I'm sure it would be very simple to remove quite a lot of watermarks (obviously would depend rather on the nature of the watermark).
I've done a little more playing with it on some very basic images. Items on a very simple gradient sky, and it's just absolutely rubbish. I always use a solar curve to check the quality of my retouching and this doesn't even stand up to visual scrutiny without it, let alone with it. I might make a little video on a random selection of images and 'quick' selections. A complete load of overblown hype IMO.