I'm glad some of the features have been fixed like this 50hz TV thing.
Anyway, here's the complete list via Major Nelson's blog:
Improved Multiplayer & Party chat
- Cross title party chat
- Party chat on by default
- Easier multiplayer invites
- Easier multiplayer joining
- Ability to see what the people in your party are doing
Improved Friends List + Profile
- Improved friends list utility & speed of access
- Ability to see people you recently played games with
- See when friends are broadcasting, including live broadcast thumbnails in activity feed
- Get to a friend’s profile faster using type-ahead suggestions
- Contextual app menu actions on friends list and activity feed items
- Enabled more multiplayer (join and invite) actions on user profiles
- 54 new contest-winning gamerpics
Twitch TV live streaming support
- Broadcast gameplay on Twitch.TV through Xbox LIVE (When the updated Twitch app ships next week.)
- Voice support for starting and ending broadcast
Bringing out social in home
- See favorite friends currently online
- See friends broadcasting gameplay
Miscellaneous shell improvements
- Improved notification center experiences including “quiet mode”
- View Game Clips while in snap mode
- Protect user settings with passkey
- Control Bing and Google maps with gesture and controller
- Quick search when highlighting a term on a page
- When searching from Bing search on the console, direct link to Internet Explorer in order to see additional web results.
New Devices – Driver and Firmware updates
- Firmware update to the Xbox One controller to support the Xbox One stereo headset adapter
- Support for 1st and 3rd party headsets
- Driver updates for the Xbox One Media Remote
- Push notification to your device for Xbox Live messages
- Quickly see what a friend is doing including presence and recent
- Enhanced viewing of personal and a friend’s game progress and clips
- Ability to close snap from SmartGlass
- 50Hz fix – users can set the Live TV app to display at 50Hz for full or fill modes
- Volume up/down adjustments – user can tailor the number of volume increments when using “volume up” or “volume down” commands
- IR blasting of power & volume to TVs/AVRs in all regions
- AVR setup maps to include model number for most sound bars or AVRs when setting up TV
Improved Audio output support
- SPDIF (optical out) now supports 5.1 Dolby Digital – enabling devices such as sound bars with only Optical In to be able to receive 5.1 Dolby Digital from console over optical
- HDMI output now supports stereo uncompressed, 5.1 uncompressed, 7.1 uncompressed or 5.1 Dolby Digital live or 5.1 DTS
And then some more via Eurogamer, it's Microsoft's product officer, Marc Whitten::
"We value all of the feedback we're getting from you," Whitten concluded. "Keep it coming! We are listening."
Whitten said Microsoft was working on external hard drive storage support for a future update, as well as friends notification improvements.
"Just as we do with Xbox 360, we'll be continuing regular updates to Xbox One - some will be big, like this March update, and some will be smaller," he continued.
"Big or small, we're committed to delivering continuous innovation through system updates like this one. Thanks for your feedback."