They're still focused on their proprietary drivers, and naturally that means that they're way behind on supporting modern kernels. That's an issue if you have other hardware that only had support added recently. Their integration with X11's autoconfig also tends to have.. problems.
Nouveau basically doesn't work for their modern GPUs. My work laptop has a 1660Ti, and X11/Nouveau still can't render anything with it. Wayland/Gnome/Nouveau kinda sorta works, but I'd rather not have to use Wayland if I can avoid it.
Nvidia's support for PRIME is lacking. Their official stance was that you should restart your X11 session every time you wanted to swap. Bumblebee kind of worked, but was very slow and unstable. It looks like they finally implemented support for dynamic PRIME now, but of course they had to name their trigger environment variable something else, so that existing scripts for AMD PRIME wouldn't work.
Unless you want to do some cutting edge stuff with it. We're begging nVidia to fix their DPMS implementation over DisplayPort for years now.
Oh, I forgot that nVidia drivers do not make enabling VSync easy for video/compositing overlays for ~6 years? I have to disable all optimizations and lose 50% performance to enable VSync in a compositing or video layer.
Yes, most of it works but some annoying parts do not work, and nVidia doesn't make anything easier.
This is on a GTX680 card. It was king of the hill when I first bought it.