At present, nouveau is only working in a handful of linux
distributions (with or without experimental hardware accelerated
3D support). All of the other UNIX-like systems are presently
unable to run nouveau (e.g. all of the BSD's)
The most important issue is actually the wasted developer time.
Countless hours of developer time have been wasted in the attempt
to reverse engineer the proprietary binary nVidia drivers for the
sake of recreating their functionality in the open source nouveau
driver. If nVidia wants the business and support of open source
developers and users, then they should provide all of the required
specs and documentation for their hardware needed to write open
If you're under no requirement restrictions, then calling the insistence
on open source code an ideology or preference is entirely fair.
If your only goal is to just play as many different games as possible,
then using linux is a bad choice from the start, and you're obviously
intending on running closed source code, so requirements and preferences
make no difference to you.
If you hope to run as much open source as possible, then buying hardware
from friendly vendors is your best bet. Your choices for both modern and
supported graphics hardware with open source support are pretty much
limited to Intel and AMD/ATI.
However, to put it gently, the performance is not close to on-par with current generation Nvidia and AMD offerings.