Oh I've used it... A LOT.
It works as well as Windows 7/Vista/XP did but with the mish-mash of both the new tiled UI & the classic desktop environment it just seems like it's going through some sort of an identity crisis.
I'm not jumping 'on the hate bandwagon' - I got bored with Windows by the time 7 came around as it was just really stale & there was no innovation (bar Aero-snap

) present. Windows 8 tried & has succeeded in spicing things up a lot & when I first saw it was impressed.
When the day comes that they learn that an ideal multi-touch tablet user interface & an ideal mouse & keyboard desktop user interface are two very different things & start to implement the changes in different form factors. THEN I'll be happy & will stop whinging