Rant: My first smartphone was a Lumia, and then when it broke i went to a Sony Xperia (with a rather clean Android 4.3 on it).
I never even realized how well-designed WP was until I went to Android. Examples:
- Operation. Nearly all of WP is easy to operate with just a thumb, single-handed. All important controls are either near the bottom or reachable by swiping. On Android, I have to reach to the top for all kinds of stuff. It's simply, apparently, an Android design pattern to put a bar with buttons on the top, as far away from my hand as possible. This is plainly ridiculous. On WP, there's a clear relationship between "how important is this action" and "how close is it to the bottom". As it should be.
- Consistency. All well-designed WP apps work the same. Swipe left/right for different screens/tabs, touch the left-side of an item for select-boxes, operations on the bottom and more operations by selecting "...". This is the same nearly everywhere, both for built-in apps and for most well-designed apps from the store.
- Cleanliness and clarity. The Xperia forced me to choose a home screen background picture, making it very difficult to read text and icons. I google-image-searched a "black.png" to work around this, but still, it's cluttered by default, and you need to do work to clean it up. Similarly, most good apps are really clean and uncluttered. I get the info I want to see or manipulate, no bullshit bells and whistles.
- Quick. WP's live tiles are a perfect middle ground for me between bloated Android widgets and app-icons-only like in iPhone. My homescreen only contains the stuff i do often, with bigger buttons for stuff i do more. All this, without cluttering the UI like doing something similar on Android would do (by hand-dragging around a combination of widgets and icons).
Needless to say, I went back to Windows Phone (anyone want to buy a Sony Xperia SP, btw?). Upgraded to WP 8.1, which added:
- The best mobile calendar app I've ever seen. The week view is simply amazing [1].
- Fix for every single thing I want that Android had and WP hadn't: better volume controls, action center for notifications and quick access to settings, stuff like that.
I'm well aware that none of the above includes the things you mention: customizability, open source, etc. WP indeed doesn't have that - it's much more like iOS in that respect. I thought I'd miss this, but with 8.1 fixing all the issues I had with WP, I realize that actually I don't want customizability, I want the thing to work great out of the box.
You only need customization if what you start with sucks.
On the hackability aspect though, WP app development is a very smooth experience compared to Android app dev (assuming you have a Windows computer ready somewhere). The API is very well designed and documented, and the tools are great (assuming you can stand Visual Studio).
[1] http://conversations.nokia.com/2014/04/17/windows-phone-8-1-...