I've been a long-time Opera user from the 90s, and version 12 is still working fine for most of my needs. However, the Flash Video Downloader extension has stopped working with Youtube, and so I'm forced to consider upgrading to Opera 20 to get the new FVD extension.
But everything I'm reading about Opera 20 is making me think it's not worth it! As long as I can install it as a standalone, then I might still do that.
If I could just get FVD's 1.8 extension to work again in downloading Youtube videos on Opera 12, I'd be happy right back at version 12.