I really like windows 10, but on new updates sometimes graphics drivers don’t follow right away, or are of poor quality, so you could end up with a not so usable system for some days, but after all it’s a preview so you don’t have to complain ;)
So personally if you want to start to use windows 10, I still recommend to use a spare drive, so you can rollback to windows 8.1 quickly in case of issues (having a faulty driver before a show is not the most pleasant thing around ;)
I didn’t tried latest version yet, but so far:
-build 10041 was pretty good on ati card.
-build 10074 was horrid on ati card (maybe now there’s a proper driver, did not try since a little while, but at the time of install it was like that).
-build 10041 was ok on nvidia
-build 10074 + driver 352.84 is for now the sweet spot here, works like a charm.
As a side note new build in the slow path is 10130, did not upgrade to it yet so I can’t tell about any driver quality.