Nouveau (open source Nvidia graphics drivers)

So I tried to install sway on my desktop today. This required a lot of fiddling, as I had to pull in bleeding-edge dependencies for the Wayland libraries, and had to build the compositor framework wlroots. Finally however, I had everything compiled and ready to go and....

Proprietary Nvidia drivers are not supported. Use Nouveau.

I had completely forgotten that sway requires open-source Nvidia drivers. So - has anyone had experience using Nouveau? How usable is it from day-to-day? How noticeable is the performance hit when switching from proprietary drivers?