*** What’s new in v4 ***
• Support for HD and higher resolutions.
• Brand new icon (similar to Windows 8 app).
• Brand new “paper” theme for great reading experience.
• Fast app resume from start screen.
• Support for small, medium and wide live tiles.
• Support for Lock-screen notifications.
• Always read complete stories using “full article mode” (powered by Readability).
• Customize article list views.
• New gestures for changing articles.
• New metro style share menu.
• New: ‘Show image captions’ in articles view.
• New: Pin ‘subscriptions list’ to start from app bar.
• Do not hide read items immediately (added option to hide instantly for v3.x behavior).
• Faster image caching by 2-3x times.
• Improved YouTube support with IE10.
• Fixed: Image resizing in article view.
• Several other UX/design improvements, bug fixes and enhancements.
>> Different layout options <<
Also, thanks to Ashish for posting a video for Nextgen Reader v4 on WPXBox