I’ve played a bit with Math equations. I changed the Metadata of the standard Ubuntu font ‘FreeSerif’ to OpenSymbol and replaced it with opens___.ttf.
The cool thing about is, that it is much prettier than the new OpenSymbol font and it is a Unicode font, and has plenty of math symbols (like double-stroke letters, frankatur, calligraphy, and many many symbols).
Since the new OpenSymbol font uses standard Unicode, it can be replaced smoothly. I’d recommend to replace OpenSymbol with FreeSerif and enhance the catalogue of Math with e.g. double-stroke letters, frankatur, calligraphy, and many symbols.
Also the appearance is really smooth if you use FreeSerif as your default font for the entire document.