I upgraded this summer from Debian sarge to etch. As part of this transition, I have upgraded from Xfree86 to X.org and from the custom 2.6.8 kernel I built to the 2.6.12-1-686 kernel provided by etch. As a result of the kernel transition, I was able to install the Debian NVidia drivers with a minimum amount of hassle. I still have to fix the symlinks to the libGL libraries for some unknown reason. As compensation, I found the documentation on how to suppress the NVidia splash screen when my X server starts.
In contrast to my old kernel, ALSA just works with the new kernel. I am much more pleased by etch than sarge.
I have been very pleased by the Debian testing distribution. I dislike running unstable because every so often something gets uploaded into unstable that breaks just about everything. This really hasn't happened with testing. I decided to upgrade my kernel and X server simultaneously, which was the most painful part of running Debian testing so far.
Etch is also testing a new GUI installer that looks very promising.