Nouveau (the reverse engineered Nvidia drivers) only work on some of the systems for some of the users some of the time(1). It is an incredible amount of work,

Nouveau (the reverse engineered Nvidia drivers) only work on some of the systems for some of the users some of the time(1). It is an incredible amount of work, and an incredible amount of functionality that they have. And they are constantly chasing advances in Nvidia's hardware, as well as progression in the Linux desktop world. As an example of Nouveau not working "fully" - I get pointer trails, incomplete drawing, no vsync, monitor not doing DPMS power down and several other glitches. As a third monitor this is okay, but it wouldn't work for a primary. Nvidia's binary drivers are generally very good providing you only want what they provide. For example it was only very recently (as in months) that they started supporting xrandr 1.4 and even then it doesn't play nicely with others. (1) The Nouveau folks don't claim any different, and "some" does often turn out to be "a lot"