The symbol lacks definition.
Too many bubbles, colours too close.
Small, looks like a vaguely triangular smudge.
If ever in print, hard to reproduce, will go very dull in process colour.

No doubt it demonstrates the rationale nicely ("a bunch of grapes, the different colours representing the variety of wine"), but if one is being literal, what has a cloud of coloured balloons got to do with wine?

FWIW I think the symbol is fine in a sense that it's the type that is a problem. It dominates the logo and dwarfs the symbol. Also the humongous whitespace between V and i looks troublesome.

I would have used a lowercase "v" for better logo recognition As Nick say too many bubbles. Have you tried a design with outline bubbles in different shades of wine?
Dr. Type

I don't know if it's the number of bubbles, or if it's their size variation. The ones in the middle look way too big to be grapes from the same bunch as the ones on the outside. Try making them closer to the same size.

- Lex