[Windows Phone 8 General] GoodDayToDie:
Some cool ideas there. A few comments (posted here because I don't see a way to leave feedback on the site):

1) I'd put the Charms bar on press-and-hold of a button, probably Search (which doesn't currently have any Hold action assigned). Double-tapping is an action that literally nothing else on the Windows Phone OS uses, and especially a button that is sometimes capacitive and sometimes physical (depending on phone model) it's not something I advocate adding now. I like the idea a lot, though, especially for its tie-in with Win8. One thing to add to the Charms bar though: as on Win8 (where it shows a bunch of status info when you open Charms), the Status Bar at the top of the screen should be always visible when showing Charms.

2) There's already a way to get to the task switcher; while it's OK to have multiple methods for achieving the same goal, it seems like there might be something more useful to do than duplicating functionality through a more round-about approach.

3) There should be a more visible cue about the notifications center. Either have something drop down from the top (perhaps a "you have <X> notifications" bar with an appbar-like pull indicator?) or add a button specifically for notifications (two-level Charms bar? Move it to the right edge of the screen? Not sure how best to handle that).

4) I know the whole "swipe down to close an app" thing is very commonly requested, and comes from WebOS, and vaguely resembles Win8, and... I still don't know if I want it. Closing an app is pretty close to literally never needed; backgrounded apps are not generally allowed to use any system resources (they may hold onto some RAM, but the system will take it from them if a foreground app needs it). Closing an app the "usual" way - by switching to it if needed, and then tapping Back until it goes away - also works, although it's more actions. My biggest concern would be that right now, it's not really possible to ever do the wrong thing on the task switcher view. Closing an app, though, is a destructive behavior - you lose the app's current state - and is something that would need to be carefully implemented to make sure it never happens by accident... or perhaps make it optional entirely.

5) The Xbox Music feature looks pretty good, although the drop-down switch between Albums/Songs/Artists/etc. might be a bit too... background. Also, the really basic problems of the new UI - things like songs getting duplicated when they exist both on the phone/SD card and on the "Music Cloud" - really need to be addressed. Highlighting the Search thing - I know you mentioned it earlier with global search, but it's good to have more focused search capabilities too - as the current lack of Search in the music app is a Problem.

6) "Windows and Windows Phone share the same store" is way, way more complex than anybody might be realizing. Leaving aside the fact that most Windows Store apps aren't written for the resolution or aspect ratio of Windows Phone and would therefore possibly look kind of crappy if they were usable at all, and the fact that app models of the two OSes are pretty different (for example, Windows Store apps are allowed to request filesystem access and are required to implement the Settings charm, while WP apps have neither of those things), the APIs are just different. WP8 can use a sort-of-subset of WinRT (the API for Win8 apps) but it's not the same thing (and Win8 can't run WP7 apps at all, not even close). Finally, there's the issue that even the most powerful WP8 are half as powerful as even the lowest-end WRT tablets, and that's going to make a lot of things that perform fine on things like Surface RT be unacceptably slow on a Lumia 920 and impossible to run on anything with lower specs.

7) IE11 is coming for sure. The sync feature would definitely be nice. I'd also like to see some version of (desktop) IE's feed reader (shared with desktop Outlook) get integrated into WP8.

8) Integration with photo services, in the same way as other parts of the phone are integrated with Facebook and LinkedIn and Twitter and so on... that is an excellent idea. Come to think of it, Facebook pictures are already integrated (a feature I never really use) so adding others should definitely be possible. It would be cool if apps could integrate that kind of stuff without explicit OS support, but that may be aiming too high.