As someone with C's, I can safely say that I agree with Hanne, for the most part. With larger breasts, they can be considered SEXY and very well coveted by MEN (no guy I know dislikes mine) but personally, I find that having larger breasts generally precludes me from wearing lower cut tops that might be cute on people that are A's or small B's, but look terribly skanky on me. I love a lot of runway looks, for example, but the looks that are featured on models are much more suited for their body-types - less breasts. There's a limitation to what you can wear safely without appearing to be ...overdoing it if you have larger breasts. I generally consider myself to be fairly fortunate to be rather proportionate, as even though I'm a size 2 (and sometimes my breasts can be...er...too large proportionally, I think) I do have hips which balance out the look. I can't push Tara Reid boundaries...
Although, the guys seem to appreciate them, so I find that amusing and rather flattering. Haha!
Now, see, if we had convertible breasts, that would be wicked...that way, one day you could choose to have A's and the next to have C's or whatever. haha.