Starting 14 april 2014, you can update your personal dev phone(s) to run Windows Phone 8.1 using the Windows Phone Preview for Developers program . Along with the tooling delivered in Visual Studio 2013 Update 2 RC, developers can now get everything they need to start building and testing Windows Phone apps and universal Windows apps. Even better, Windows Phone Store is also starting to accept app submissions and to enable app linking today – enabling you to bring the universal Windows app experience to your beta users and consumers.
To update your Windows Phone 8 device to 8.1, you will need to download the app and opt into the program (the process is outlined on the Windows Phone Dev Center); if your phone is already opted in, then all you should need to do is head over to your phone’s settings and check for an update.
To update your Windows Phone 8 device to 8.1, you will need to download the app and opt into the program (the process is outlined on the Windows Phone Dev Center); if your phone is already opted in, then all you should need to do is head over to your phone’s settings and check for an update.
Features included in Windows phone 8.1
Cortana
Cortana is a personal virtual assistant that was added in Windows Phone 8.1, and is similar to Google Now and Apple's Siri. The Cortana name derives from the Halo video game series, which is a Microsoft franchise exclusive to Xbox and Windows. Cortana's features include being able to set reminders, recognize natural voice without the user having to input a predefined series of commands, and answer questions using information from Bing (like current weather and traffic conditions, sports scores, and biographies).
Cortana also uses a special feature called a "Notebook", where it will automatically gather information about and interests of the user based on usage and allow the user to input additional personal information, such as quiet hours and close friends who are allowed to get through to the user during these quiet hours. Users can also delete information from the "Notebook" if they deem it undesirable for Cortana to know.
Windows 8.1's universal Bing SmartSearch features are incorporated into Cortana, which replaces the previous Bing Search app which is activated when a user presses the "Search" button on their device.
This feature will be released in beta in United States in the first half of 2014 before being publicly available in most other countries by late 2014 or early 2015.
Multitasking
Building on improvements made in the third update to its predecessor, Windows Phone 8.1 adds support for closing apps by swiping down on them in the multitasking view (invoked by doing a long-press on the "back" button), which is similar to how multitasking operates on iOS. Pressing the back button now suspends an app in the multitasking view instead of closing it.
Live Tiles
A third row of live tiles, which was previously available only to Windows Phones with 1080p screens, is now an option for all Windows Phone 8.1 devices regardless of screen size. Microsoft has also added the ability for users to skin live tiles with a background image
Lock screen
Windows Phone 8.1 adds the ability for OEMs and individual apps to customize their custom lock screen themes even further by skinning the font and orientation of time, date, and notification text.
Notifications and settings
A new notifications center known as "Action Center" has been added, and allows for the ability to change simple settings such as volume controls. The new notifications area's design allows the user to for example change wireless networks, turn Bluetooth and Airplane Mode on or off, and access "Driving Mode" from four customisable boxes at the top of the screen, while beneath these four horizontally placed boxes include recent text messages and social integration.
Apps can also send users location-specific notifications with the addition of a new geofencing API.
Keyboard
Microsoft has added a "Word Flow" keyboard in Windows Phone 8.1, which is similar to the "Swype" keyboard option available on Android devices, allowing users to swipe through letters to type. As the user swipes, the keyboard generates space automtically for the next word to be entered.
Fifteen-year old Lakeside School student Gaurav Sharma, using a low-end Nokia Lumia device equipped with Windows Phone 8.1 and the "Word Flow" keyboard broke the Guinness World Record for the world's fastest typing on a mobile phone, which was previously held by a Samsung Galaxy S4 user, by 8 seconds
You can check more feature and Details on windows phone 8.1 on
source: http://en.wikipedia.org/wiki/Windows_Phone_8.1#cite_note-NDTV-16
Cortana is a personal virtual assistant that was added in Windows Phone 8.1, and is similar to Google Now and Apple's Siri. The Cortana name derives from the Halo video game series, which is a Microsoft franchise exclusive to Xbox and Windows. Cortana's features include being able to set reminders, recognize natural voice without the user having to input a predefined series of commands, and answer questions using information from Bing (like current weather and traffic conditions, sports scores, and biographies).
Cortana also uses a special feature called a "Notebook", where it will automatically gather information about and interests of the user based on usage and allow the user to input additional personal information, such as quiet hours and close friends who are allowed to get through to the user during these quiet hours. Users can also delete information from the "Notebook" if they deem it undesirable for Cortana to know.
Windows 8.1's universal Bing SmartSearch features are incorporated into Cortana, which replaces the previous Bing Search app which is activated when a user presses the "Search" button on their device.
This feature will be released in beta in United States in the first half of 2014 before being publicly available in most other countries by late 2014 or early 2015.
Multitasking
Building on improvements made in the third update to its predecessor, Windows Phone 8.1 adds support for closing apps by swiping down on them in the multitasking view (invoked by doing a long-press on the "back" button), which is similar to how multitasking operates on iOS. Pressing the back button now suspends an app in the multitasking view instead of closing it.
Live Tiles
A third row of live tiles, which was previously available only to Windows Phones with 1080p screens, is now an option for all Windows Phone 8.1 devices regardless of screen size. Microsoft has also added the ability for users to skin live tiles with a background image
Lock screen
Windows Phone 8.1 adds the ability for OEMs and individual apps to customize their custom lock screen themes even further by skinning the font and orientation of time, date, and notification text.
Notifications and settings
A new notifications center known as "Action Center" has been added, and allows for the ability to change simple settings such as volume controls. The new notifications area's design allows the user to for example change wireless networks, turn Bluetooth and Airplane Mode on or off, and access "Driving Mode" from four customisable boxes at the top of the screen, while beneath these four horizontally placed boxes include recent text messages and social integration.
Apps can also send users location-specific notifications with the addition of a new geofencing API.
Keyboard
Microsoft has added a "Word Flow" keyboard in Windows Phone 8.1, which is similar to the "Swype" keyboard option available on Android devices, allowing users to swipe through letters to type. As the user swipes, the keyboard generates space automtically for the next word to be entered.
Fifteen-year old Lakeside School student Gaurav Sharma, using a low-end Nokia Lumia device equipped with Windows Phone 8.1 and the "Word Flow" keyboard broke the Guinness World Record for the world's fastest typing on a mobile phone, which was previously held by a Samsung Galaxy S4 user, by 8 seconds
You can check more feature and Details on windows phone 8.1 on
source: http://en.wikipedia.org/wiki/Windows_Phone_8.1#cite_note-NDTV-16