I switched to 10 yesterday, and after installing and activating it, I downloaded the Nvidia drivers. Most of the pack simply didn't install. It seems the driver for my GTX750TI is marked as Nvidia, yay for that. It also looks like I have a Nvidia control panel, but nothing happens when I try to open it.
They need to do better than that.
That said: I only installed and tested one game before heading for bed. Bioshock Infinite. It ran just as good as it did on Windows 8.1. ..and so far I like the OS. Would love a SM Bus driver for my Z97 board though.
-EDIT-
Today i was able to find Windows10 drivers on my motherboard manufacturer's webpage. Some of them were uploaded yesterday. i may have tried to find them when they were messing with the site.
Either way: Installing the original chipset drivers made the Nvidia driver package work. My apologies to nvidia for moaning earlier today. Everything's fine now