It matters to a certain extent. Personally, I'm not attracted to very large breast sizes. If it's bigger than a large C, I won't initially find that attractive. I also don't like extremely small breasts, like anything less than a large A. I find that middle range incredibly attractive. Hand size, I suppose! However, there are some people who are anomalies, and if I get to know the person and am attracted to them, then I don't care what their cup size is. I won't necessarily pick them out on the street, though (not that I hit on people on the street, but just look their way, I mean).