There is a negative: there's no security yet. In other words, you can't password protect the content, meaning that anyone with the link has access to the file or folder.
The changes include a Get Link function when looking at your files (shown above). You right-click on the paperclip symbol to bring up the context menu, and then click on "Get link," and DropBox will create a custom URL for you.
The recipient of the link can then view the content located at the URL directly without having access to the rest of your Dropbox contents. There's no download required; they can they watch a video, view a photo, or read a document directly in the browser.
The timing couldn't be better. Google is rumored to be launching its online storage service, dubbed Google Drive, soon, perhaps as soon as this week. Dropbox desktop, web, and mobile applications are all, or will all, be updated to support the new functionality.