Personally, I’ve found testing’s stability to be horrible. Especially the desktops. And I don’t mean ‘unstable’ as in ‘lots of crashing’.
First, I used GNOME. Debian changed their setup in a way that broke Ximian (which was pretty poor anyway), so I switched to the main packages. Only to find that a lot of programs were the old, buggy versions, while others were the newer, nicer versions.
Fed up with GNOME, I switched to KDE. All nice… Up until the recent kidelibs3 upgrade. Somehow, kdelibs3 2.2.1 got moved into Testing… Without any of the other KDE 2.2 stuff. This, predictably, broke almost everything. (And no, it wasn’t a force-overwrite install that did it. That just overwrote a bunch of pngs) Alt-tabbing locks the system, kmail’s pop3 support no longer works, konqueror’s just plain broken…
And that’s just the latest in a whole line of poorly-thought-out and executed changes like that. I’ve had my resolv.conf erased three times, and numerous incompatible changes in packages that aren’t documented or warned of anywhere. And fixes for anything take ages to move into Testing from Unstable.
Am I using the wrong mirrors or something? Testing seems far less ‘stable’ than any of the reports I’ve heard about unstable.