Nails
A quick play with the Preview version of WP10 was what finally pushed me through the door with the green robot on it. Despite a deficit of apps WP8.1 is the most logical and user friendly mobile operating system I've used. Coupled with some great handsets from the now decimated Nokia (I've kept my 1020 for the incredible camera) and Microsoft looked as if they were onto a winner.
But as is they're way: if it ain't broke, repeatedly punch it until it's utterly FUBAR.