The whole tablet UI switching had huge potential - particularly for 2-in-ones and to a lesser extent, mobile devices, but Microsoft absolutely butchered it in its infancy with atrocious execution, and by having the hubris to hobble their primary use-case (desktop) for the sake of pushing their half-baked nonsense into the mobile market. Users didn't do themselves any favours by not understanding that you could just hit start then type the first couple of letters of what you want to launch (what kind of website double-clicking weirdo clicks through the whole start menu without pinned links or search anyway?).
To me, it all reeks of designers/PMs/devs putting forward a super-promising concept, which was ruined by a bunch of overpaid MBA dipshits that thought they knew better.