The first time you launch News, it asks you for some details including selecting the news sources that you're interested in. What I noticed is the news sources available are free, I couldn't spot the usual paid news sites that I see on Newsstand. Perhaps this is deliberate, or maybe paid sources will be coming in the future. I certainly think that removing these paid for or '10 articles free per week' sources adds to a better experience within the app, which is something that always put me off when using Newsstand.
You can add any number of news sources to your favourites list, the explore tab lets you select more sources to add or simply browse if you just want to see the content that one time. These features are also available in Newsstand, however to access them you have to tap the menu button at the top left and navigate from there. In News, the process is a lot simpler.
The 'For You' tab in News is very much like the main Read Now part of Newsstand. This basically aggregates all of your news sources together into one big list of articles. I actually prefer how Newsstand separates this into further categories e.g. World, Entertainment, Technology, etc.
The search page is just what it says, it lets you search for news but also gives you suggestions which I guess are tailored by current trends since the list I saw didn't reflect my interests in the slightest.
What I really liked with News is the ability to quickly bookmark articles and how easy it was to access these articles later. Again, this feature is present in Newsstand but is so much harder to access in my opinion. News gives you a bookmark button at the bottom of an article and a tab titled 'Saved' to access these articles. It just feels seamless.
So is News a Newsstand killer? At least for me it is. It also means that I don't need to have yet another app for a simple task such as reading news. iOS should have had this app a long time ago. Overall I think that News has a much better usability experience than Newsstand, but it does lack some of the little things that Newsstand gets right, but I'm sure this will get ironed out in future versions.