It would be nice if the nvidia drivers were opensource, however they are not. At this moment I think it's bad to bash nvidia about that. They are making some rather good drivers and seem interested in having their hardware working under linux unlike many other companies who seem to ignore the fact that linux users, albeit a mere bleep in their radars, also buy graphics cards and will buy the ones that work. Well, from my experience, nvidias work best.
There is room for improvement, the drivers could have new releases more often (they could release official "this may melt your card" betas to expose bugs sooner) but I guess there is more time being invested in the windows drivers that the Linux/FreeBSD/whatever ones (unfortunately).
There is one thing that seriously bugs me tough, which seems to be the reason most folks want opensource drivers, it the "what if they drop support" feeling. This is a risk, and this is the reason I would also like to see opensource nvidia drivers (but if they keep up the good work they are not strictly necessary).
But I don't resist asking them to opensource as much as they can from the drivers, at least that NvAGP stuff could be opensource. What's the reason to have agpgart and nvagp when agpgart is even the default...?
As a final note, nvidia should release the specs for their older cards (like the TNTs) to the maximum extent possible (of course if there are bits in common with their recent products this may be difficult). This way we could see this hardware working as it should. I have TNT2's in use in several computers and the nvidia drivers still have the very same bugs they had years ago. The nv driver, on the other hand, works ok but doesn't support Xvideo or OpenGL (these cards are mainly for 2D but sometimes 3D accel is useful for those nice GL hacks from xscreensaver). My Geforce works perfectly tough