A leaked version of Windows 10 build 9901 reveals some of the new consumer features Microsoft is developing for its upcoming operating system, you can view a bunch of screenshots at SuperSite for Windows. Among other things, the build introduces an improved version of Cortana, a unified Store app, a new Settings app, new visual styling, etc.
A more fleshed-out version of Cortana, Microsoft's voice-activated digital assistant, complete with a search field right in the taskbar.
A unified Store app that combines "apps, games, music, and movies & TV" with "document-style vertical navigation" (meaning, hopefully, no more horizontal scrolling).
Revamped Xbox and Photos apps.
A new Settings app that "shows how Microsoft may replace both PC Settings and Control Panel with a single UI." Microsoft replacing Windows' weird mish-mash of new and old control panels seems long overdue.
Plus some visual styling changes, including a black taskbar, new buttons on Modern UI window frames, and a handful of fresh wallpapers.