The only thing not working is sound, which for some reason is highly distorted or nonexistent. Some of the folks at the InsanelyMac forums have figured out a process that works. We haven’t yet tested it ourselves, but we’ve heard good things. It promises to take you through the process of installing and setting up a macOS virtual machine. If you want to install a newer version of macOS in VirtualBox, check out this script on GitHub.
Update: The instructions here apply to older versions of macOS.