They have even criticized Nvidia specifically for not releasing free drivers. Nvidia responded.

NVIDIA's open-source Linux efforts as it concerns their GPU support have historically been minimal. The xf86-video-nv driver has been around that provides very basic 2D acceleration and a crippled set of features besides that (no proper RandR 1.2/1.3, KMS, power management, etc) while the code has also been obfuscated to try to protect their intellectual property.

The Free Software and Open Source community is always asking for hardware manufacturers to write free and open source software (from now on called FOSS) drivers. So, let's try to guess what would happen if nVidia decided to release the graphics drivers as FOSS.

Currently, GNU/Linux users with Nvidia graphics cards have two choices: Either use the proprietary drivers and violate their free software principles, or use the free nv driver and do without 3-D acceleration. The Nouveau project is working to overcome this dilemma by producing its own set of fully functional free Nvidia drivers.

It's been no secret that NVIDIA has been working on an OpenCL Linux driver for their graphics processors just as AMD has been doing, but up until now their beta drivers were only available to registered NVIDIA developers. Today though -- on the same day as NVIDIA's OpenCL driver launch for Windows -- they have made their OpenCL support publicly available.

Back in March an announcement came out of NVIDIA as they were getting ready to launch the GeForce GTX 400 "Fermi" graphics cards that they would be dropping support for the xf86-video-nv driver.

In time for the X.Org 7.5 release (whenever that may come), David Airlie has put out new driver releases for nineteen of the X.Org video drivers. These aren't updates to the mainline ATI/AMD, Intel, or even NVIDIA drivers, but some of the drivers for less common graphics hardware.

We the GNU/Linux community and the undersigned, kindly request that you, NVIDIA Corporation, increase your efforts in better enabling the open-source community to develop free software drivers for your graphics hardware. Your major competitors in this market, AMD/ATI and Intel, have not only supported the community in open-source driver development efforts but they are now openly releasing hardware programming documentation.

Nvidia drivers, like it's propriety counterpart, ati, have a tendency to break. For some computer users, it breaks a lot. The open source drivers, vesa and nv, from experience, do not break on my systems.