The grapes are not very good for eating off the vine since they are tiny, pretty sour and full of seeds. However, we have used them to make delicious grape juice and grape jelly - think Welch's but better. The grapes do sweeten up very late in the season but by then most of them have been devoured by either the birds or the hornets.
The key to a superb grape harvest, you ask? We have it figured out - it is essential to trim the vines right back to the main stem after the growing season. This is a tip we picked up from visiting the vineyards in Niagara in the off season - all their vines were pruned right back. We figured if it works for them, it might work for us too - and it did! Here's to a very grape-y summer.