I've had three SiS-based motherboards (645dx, 648, and a 655)... All of them had some sort of issue.
i.e. Wouldn't shut down properly, USB wouldn't work sometimes, having to reset the multiplier/fsb sometimes after restarting, had to revert to an earlier AGP driver to get video drivers to work, etc. Nothing that would crash during an application, but it certainly was an annoyance.