A co-worker grew one. It gave a nice harvest a couple years but didn't produce anything after that. Granted, this is in Texas with very hot summers and clay soil.

He was happy with the fruit, although it bore little resemblance to a real Concord grape. It didn't have the intense flavor, there wasn't much of a slip skin or velvety-mushy heavily pigmented material underneath, was practically odorless, had no measurable methyl anthranilate or aminoacetophenone, the color was more red purple than blue purple. And a few other things. I think it was false advertising to call it a "Concord" (that particular one at least).