-Start screen backgrounds and a color picker for theme color. That MS chooses to be stubborn about this, rather than listening to customers and giving the OPTION of customization is frustrating and a huge limitation to the otherwise beautiful WP start screen.
-More rows of live tiles, and more live tile sizes. Also, I'd love to see the SDK expanded to give more customizable live tiles, and so devs can allow users to customize their live tiles more.
-Fix Skype. It's awful on WP.
-Settings menu needs to be overhauled.
-Music app should be better. Playlist creation is atrocious and editing playlists is next to impossible. Optional live tile w/ artists or albums. Smart DJ needs improvement.
-Gapless audio playback.
-Overhaul of the "Windows Phone Store". It's ugly and not user friendly. Their Metro UI panels are not useful. Searching the store is terrible.
-IE 11 needs work. More than 6 tabs. Open new tabs in background, better access to favorites, bezel swipe to go back, etc.
-Make the messaging app more visually customizable. Add a iMessage rival, or integrate Skype messaging deep into the OS. Mass deletion of texts, search button, customizable keyboard. Currently if you add an additional language to the keyboard, the language key steals from the spacebar and makes everything cramped.
-Mail is boring. Get the Outlook team to design it. Windows phone needs to realize it is possible to be minimalist without being boring. Bring sweep from outlook to WP mail.
-The Phone app is lacking and the dialer is terrible.
-File Manager.
-Better Multitasking. The current method is confusing and inefficient. Ability to pin apps to the other side of the multitasking view for quick access.
-Search the whole phone or cloud.
-Ability to reply to texts from within the Action Center.
-Expand Bing outside the US.
-More help when setting up the phone.
-A few more
Stuff that would be cool but is unlikely/possibly a bad idea:
Thoughts? :
-Move the OS to the cloud. Customize/optimize what you want, and then download it to your phone. Keep the OS light and simple if you desire, or give power users better control. A settings wizard that could ask you questions and help design your WP.
-Allow the creation of multiple start screens. Like, you can save several combinations of theme colors and start screen configurations. If you start screen gets boring- select one of your saved ones, and it's there.
-Split the Windows Phone Store app/games store from the music/video options. "Windows Phone Store" merges with the "Windows Store" in Windows 9 when Windows/RT/Windows Phone become unified. One store for all your apps and games.
-Put Bing at the head of entertainment services- rebrand Xbox Music and Video as "Bing Music" and "Bing Video". People purchase entertainment content through Bing.
-Video Pass? Similar to Hulu. Tiered subscription model- minimum price could get unlimited streaming with ads, and some offline downloads for traveling. Microsoft could even invest Hulu and use their service.
-Allow WP to access the HDMI passthrough on Xbox One- watch tv in any room via Miracast, or even remotely over wifi.
-Swipe to the left on start screen brings you to "Bing Live". Basically aggregates the Bing Suite of apps (News, sports, entertainment, health, finance etc), and all your other services to provide proactive, Google Now-esque services. Links with Cortana and other MS services.
-Rather than having to dictate things like Siri, ability to type to Cortana through a input box in the Action Center. She suggests things as you type, learns about you over time (if permitted), and syncs to your other devices. Because no one likes to talk to their phone in public, and everyone hates it when you do.
-Cortana always has things ready based on context. For example, in Action Center, she has a list of things ready based on where I am/what I just did/what I usually do. I.E., if I get in my car, she'll prepare "Drive Home", "Open Maps", "Turn On Driving Mode", "tell __ I'm on my way", "pick up milk", etc.
-With permission, Cortana can have full access to the system and a blazing fast predictive menu. So if I type "text", she suggests people I text most, and if I click on their name, she'll have some likely texts ready, or allow me to type my own message. She can modify settings, and make suggestions. If I type: "Check Stocks", she has my stocks pulled up in a snapshot pane, with all my finance apps, related websites, or bing search just a tap away. Or if I check stocks often, she'll suggest it as soon as I type "ch".
-Just make Cortana better than Siri and Google Now so that she's a flagship feature.
-Tabs in the Store.
-Pressing and hold apps in the app list has an option to open the app in the background of your multitasking view.
-Split screen for larger devices.