They're a really good thing for the websites themselves, as you're providing them with backlinks. That's why sites like the BBC offer news feeds.
You get regularly updated content on your site, so your visitors have something new to read. However, that content links to the news provider (such as the BBC), giving them the traffic (not you). As far as Google is concerned, the content you're adding is duplicate as it's a feed from another site, so it won't do you any good from an SEO point of view.
If SEO and rankings are your concern, stop using feeds and write your own content. If you just want to give your visitors regular content without doing any work, then keep using the feeds.