Word Flow keyboard
As anyone who's used Swype or a similar gesture keyboard knows, it's hard to go back to tap-based typing once you've gotten used to swiping. Now that Windows Phone 8.1 includes a “Word Flow” gesture keyboard of its own, using the standard software keyboard in Windows 8.1 seems like a big downgrade. Word Flow should be on Microsoft's to-do list for future Windows tablets, pronto.
Now, onto the Windows features that could make Windows Phone even better.