Windows 10 is great so far.
As Hill62 pointed out, drivers for Hardware will be the issue. Roland (Edirol), for example took aged to release drivers for Windows 8. Forget the fact that it had been available in preview form for a YEAR before public release. It was pathetic.
Even more pathetic is that their Windows 7 drivers COULD have worked fine, but they wrote their drivers to NOT install if the operating system wasn't specifically Windows 7. Most other drivers wont lock you out that way.
I'm hoping these companies wake up this time, download the Preview version of Windows 10 (like every other hardware manufacturer has), and write/test their drivers BEFORE we need them. Not after.
Jeeze. Do I rant much or what?!