I owned a Windows Phone for 18 months.
Of the two locked-in, walled garden phone ecosystems the UI was infinitely better than Apple's Fisher-Price-looking iOS. What killed it was the lack of app support and the dithering over the future direction.
Was glad to get back to Android in the end.
Also MAJOR SOFTWARE COMPANY IN DISCONTINUING UNDERUSED PRODUCTS SHOCKER - FILM AT TEN
They all do it.