did you read the title of the thread?? "Aero-Glass in Windows 8 RTM, by re-instating the Aero Source Codes"
He actually pointed that out, I've used it too on Windows 8 but I've also tested it on 8.1 (and it didn't work). Anyway the developer is working on Windows 8.1 support but will probably release a build only after 8.1 gets out of Preview.
Works really great for me, how was it unstable for you? The program has come a long way from the preview versions...