One advantage of presenting a story as hard news are that you can convey a story in a very direct manner and makes no allowance for interpretation. It is most suitable when facts and figures are being presented, and if there is a large amount of detail it can be broken down into a hierarchical structure that makes it easier for the reader to take in the most vital information first. Also if the subject of the story is quite dry but important (eg. interest rates) the crux of the story needn’t have more detail than is necessary.
Soft news can present a story with more background, and offer descriptions and observations of the writer. One limitation of presenting news in a soft writing style is the word limit – there is no room for too much description. Another is that depending on style of writing it can be biased to a certain point of view.
I think life interest stories would use soft news more effectively, as the article could accommodate more descriptions. Stories based on culture and hobbies, and reviews, would generally make for good soft news.