OK, here goes my critique, never done it before so ....
I love the colour green but I would prefer a darker background to make the grapes stand out more, not necessarily a black background or anything but just a few shades darker than it is already.
I love the fact you've used natural daylight and not an on camera flash, I have such a hatred for on camera flash I feel my blood physically boil when I see it in photos.
I feel the grapes are a bit 'soft' without much texture and no definite sharpness of focus, maybe wetting them first to catch the light and brighten them up could be an idea and I'd also like to see you go in a bit closer too or else change the composition of the grapes rather than having them straight down the middle in a line.
Hope that was OK, please don't hate me!