Everything you said and more, OP! Funny thing is, I used to be a HUGE open source ***** in college. Everything I had ran Linux. Android came out after I had graduated, but I was still all over it. What changed my mind was Visual Studio 2008. After using that, I realized that MS was starting to make a turn about. I ended up on Windows 7 and haven't really looked back. I switched to Windows Phone because I felt like Android was getting boring, even with the open sourced nature of it. Tinker with it was fun, but I don't have time or patience to make my own kernel tweaks or build my own modules to do this or that. Windows Phone 8 works great out of the box, and the UI that MS has tossed into the phone and desktop versions are really keeping my interest in the company.
Also, what OP says about notification hubs is something I've been scratching my head about for a while. Your start screen makes a great notification hub. There's no need for a shade if you just hit the home button...
The only thing I may be interested in besides this is (sorry) Ubuntu's mobile and the way it seamlessly switches to a desktop mode from the phone mode. It seems intriguing and useful, though, I couldn't develop in my favorite framework (to say I'm in love with .NET and C# and F# would be an understatement). All-in-all, it's a cool concept that I hope other companies pick up, especially those that make and distribute OS's (hint hint, Microsoft). As of right now, though, if I got an Ubuntu phone, it'd just be to toy around with, but not actually use as a daily driver.