I could answer this question with one word: everything. I doubt that there is anything on Windows Phone that has not been touched up, enhanced or overhauled. Trying to review Windows Phone 8.1 will almost be like trying to review a different OS from the one that we are used to. There are so many new features added to the platform that this might just take a while. So, I have attempted to list as many of the changes as are important to the regular smartphone user as possible.
Start screen backgrounds with parallax motion. Screenshot button combination is now Power + Volume Up. Back button no longer closes apps, instead it suspends them. Swipe down to close apps in multitasking view.
Alerts, notifications, update history, quick access to Wi-Fi, Bluetooth, Flight mode, Rotation lock, Screen brightness, and Settings. It also displays date and battery percentage in top right corner.
Calendar has a new, more functional look, especially the weekly view. You can also move forward and backward by swiping horizontally. Google calendar support, with multiple calendars. Weather in calendar.
Internet Explorer 11
The email app comes with a new feature that monitors your usage patterns and adjusts email sync to that pattern to save your battery and data. New Google support for synchronising email, calendars and contacts.
PS: If after upgrading to 8.1, your Gmail account throws up synchronisation errors, simply delete it and set it up again. During setup, select “Google” and complete the process. It should work fine after that, synchronising your mails, contacts and calendars.
Mute Thread – Optionally silence text threads, no longer receive notifications or Live Tile updates.
Music Hub is gone. In its place are separate Music, Video, Podcasts and FM Radio apps.
This lets you monitor which apps draw the most power. You can also disallow apps from running in the background.
A completely new interface, and the ability to group photos by time and location. There is auto upload to OneDrive. Favourite photos by tapping a heart icon.
Store & Apps
The Store has a new, more functional look too. Now you can allow store apps to be updated automatically, and choose whether this happens only on Wi-Fi or on mobile data as well. Apps can now be installed on memory card.
Swipe typing built-in.
Did I miss anything out? Hit me up in the comments section. Version 8.1 is Windows Phone on steroids.