If you think these grapes looks like any ordinary 'black' grapes, then you ought to give it a try. The thing is, they taste like Gummy Bear candies!
And the way to eat these grapes is not to pop it into your mouth and chew. You should pluck it from the stem, hold the grape with 3 fingers, with the part that is detached from the stem kissing your lips, suck the fruit into your mouth leaving the grape skins behind. :)
Check out Tiff's posting on these grapes and about Hwaseong.