I am convinced that deanjo is getting a nice paycheck for this. Nobody can spew so much FUD for entertainment alone.
The fact is that 99% of all games ever released on Linux work great with AMD OSS drivers. I dare you to find one that does not work. I run a GTX 560 at work (+blob) and an HD4550 (+oss drivers) at home and honestly, the Radeon offers a better desktop experience.
That's not to say that the nvidia blob is bad, it just suffers from the standard problems these blobs have. The nvidia blob certainly offers fast and complete OpenGL 4+, but struggles with simple things like randr and kernel upgrades. Recently, it has struggled with resizing in KDE, totally broke gvim, and before that it fried your graphics card. It's software and all software has some bugs. The Mesa + kernel drivers are the proper way to support hardware under Linux, and here AMD is well ahead. The OSS drivers are slower, but perfectly sufficient for most people and most tasks. Especially if you plan to game on Windows. They support most of OpenGL 3.0, are at 75% of Catalyst in many benchmarks (and optimisation work is not yet finished), have decent powersaving, excellent 2d and randr support, and are really stable. Not quite as fast as the blob, and no GPGPU atm, but everyone should decide on their own where their priorities lie.
In general, it would be a good idea to simply ignore anything deanjo says about OSS drivers, or any OSS project, because it tends to be 90% false information. It's nauseating how much of what he wrote in here is wrong.