I've done it a couple times.
First time I had it install straight to the SP1 and kept everything. All my apps and such worked just fine. But I decided that W10 isn't really ready for the touch interface and went back to W8.1. THAT was not fun at all!!
Now I just finished installing it in a VM. I got the free VMWare Player and then got the 32-bit version of W10 and the install was slick as could be. I even had it get the info from the OneDrive backup so I wouldn't have to fiddle too much to get things the way I want them.
In a VM it works just fine though it is a bit slower. Not enough to irritate, just a little. The advantage of using the VM is that I can just delete it when I'm finished fiddling around or when the release version comes out next year.
One note. Since taking the SP1 back to W8.1 was such a PITA, I've since made an image with my WD version of Acronis which would make doing a complete restore much easier and smoother. Or at least that's what they tell me!!