While it is considered one of the more romantic looks, ruffled shirts should be worn with care. They often add an unnecessary (and unflattering) layer to tops, which without any real structure, make a plus-size woman look bigger.
The key to ruffles is proportion. For plus-sizes, ruffles look best on sleeves. If you are going to wear ruffles around the neckline, stick to one ruffle and make sure it's not too big. A ruffle that is too big looks unflattering to your bust; too small and it makes the rest of you look even bigger. To be on the safe side, minimize ruffles and relegate them to shirt sleeves.