The ATI open source drivers are pretty good, the NVidia's were not so good last I checked, and everything else is a crapshoot for even correct modesetting.
For 2D yes, but for newer models OpenGL is incompletely implemented and the performance is worse than on an integrated Intel chipset. Unfortunately, AMD's Catalyst blob is oftentimes buggy, or doesn't support the latest X.org and is generally a nightmare to configure when not using a completely standard setup. Nvidia's blob at least works mostly flawless while the open source Nouveau driver is far behind in terms of completeness and performance.
All in all, there is no way around the proprietary drivers at the moment if you want to use the full capabilities of your hardware under Linux. That has been the situation for years and it seems unlikely to change anytime soon.
But maybe they're doing some clever reverse psychology