True.
Unless your hugely interested in what Vista is going to look like, there's no point in using the Beta. I most definitely wouldn't treat it as a working, stable OS (or at least as close to it as you tend to get with Windows
).
Definitely wouldn't bother trying to game on it. Until the hardware manufacturers start releasing 100% compatible Vista drivers it's not likely to be happy running the game. Especially not since Vista has radically altered how the HAL works.