Facebook is an ever changing social network, it's what helps them stay ahead of everyone be the biggest social network in the world. One huge problem though is how cluttered the news feed is and that's exactly what Facebook wants to fix.
This new design is as they've said "a spring clean" for the news feed. With photos playing a huge part of the site and being the most popular way to interact, Facebook are making photos on your news feed even bigger. Thumbnails are now huge and you see more of them if a whole bunch of pictures have been added to an album.
Friends actions are now more prominent in the news feed. When a friend shares or likes an article, a video or anything across the web, it'll show very prominently on the news feed. When they check in at a restaurant, as well as giving the restaurant name, it'll show the restaurant on a map too. These sorts of actions are now a lot larger on the news feed so they're noticed.
On the right hand side of the main news feed you get some options. They're categories for the news feed so you can look at other specific content, such as updates from people you follow, most recent news, music listened to and much more. Facebook want you to be able to explore the site more, look at more updates and generally interact more with the site.
This design was hugely inspired by the mobile versions of Facebook. They want to unify the experience between all platforms so it looks similar wherever you look at Facebook.
I personally think this new design is awesome and actually looks good. But user experience is a whole different matter, that can only be judged once you start using it on a daily basis.
This new design will be rolling out slowly but you can sign up to get it early right here. That page also shows a neat demo of what it will look like on your screen.