While it's nice that there's now "out of the box" support for having open-source accelerated graphics with the NVIDIA GeForce 600 "Kepler" graphics cards on the Linux desktop, you're best off using the closed-source NVIDIA Linux graphics driver. The Nouveau Kepler driver is many times slower than the NVIDIA binary driver, lacks proper power management and re-clocking, doesn't support VDPAU PureVideo decoding/encoding of videos, and numerous other limitations. Even for NVIDIA GPUs that are a few generations old, the closed-source NVIDIA driver is much faster.
Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.