Windows Phone 8.1 - Developer Preview. (KP's first thoughts.)
It is easy and for free to register yourself as a WP developer and thus skip the awful waiting time until WP 8.1 goes official a few months time from now. It may however void your warranty, so you'll have to consider that first. Personally I couldn't be arsed to wait and here are the most important new things I've seen and played with on my Nokia Lumia 925 for a few days now.
Seperate media/ringer volume. Works like a charm.
Notification center. Pulled down from the top. A great addition to live tiles. More info when you need it. Also there's 4 quick buttons of your choice (wifi, bluetooth etc.)
The Start page top symbols (wifi, battery etc.) are always visible now.
The "Me" tile has lost the built in Facebook app. It will now launch the MS Facebook app.
The shop has been revamped completely (auto updates are now possible if you prefer so.)
The media player has been changed. It also seems to make a small amount of noise after each MP3 played, but I guess it's just a minor bug they'll fix soon.
The keyboard has been updated with "Swype" functionality (not all languages yet.)
There's an option of more tiles pr. row on the Start page. However they'll be very tiny unless you have a big ass screen.
The Battery Saver has been enhanced a lot with battery usage info per app and more.
"Cortana" has been introduced. It's an iPhone "Siri" like assistant. It's perhaps not perfect yet, but especially the voice recognition is very impressive. (switch to Region "US" if outside the US to enable it.)
The calendar has been revamped. It looks much better now (with e.g. Week view), but the tile still only shows one appointment and the input defaults to US 12 hours time (probably just a minor bug.) Until they expand the live tile to show more appointments then I'll stay a fan of "Chronos" for display.
There's more options for pinning various functionality to the Start page.
There's a lot more new stuff to explore. This is just what initially impressed me most. It's a kick ass upgrade and it sure has matured the Windows Phone system even more. Awesome work, Microsoft!!! Keep up the great work with the next updates later this year.
How to get the Developer Preview
Chronos calendar app
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