Apart from VirtualBox being notably slower (and less complete in working D3D/OpenGL support) than f.e. Parallels Desktop, I can't say I've had any gripes or stability issues with it, barring a recent, short-lived bug that caused VBox to automatically power down an active VM as soon as it went idle. I've been using VBox on OS X for a bit over 2 years now, for development purposes related to Windows XP, OpenBSD, one or two Linux distributions, and even Haiku.
Comments
Apart from VirtualBox being notably slower (and less complete in working D3D/OpenGL support) than f.e. Parallels Desktop, I can't say I've had any gripes or stability issues with it, barring a recent, short-lived bug that caused VBox to automatically power down an active VM as soon as it went idle. I've been using VBox on OS X for a bit over 2 years now, for development purposes related to Windows XP, OpenBSD, one or two Linux distributions, and even Haiku.