In short, you can have colour notifications for particular contacts, as well as the ability to swipe in to get to those favourite contacts quickly. (pocket-lint.com)
Another tab along the right rail shows upcoming and past events that you have shared with particular contacts, linking directly into the also - new calendar app. (theverge.com)
You can access the Priority only settings here, if you want events, messages and calls from particular contacts, and whether you let repeat callers through. (pocket-lint.com)