At the same time, user-defined functions solves a big pain-point with SASS at the moment. The older style of SASS functions were a very limited form of macros.

At the same time, user-defined functions solves a big pain-point with SASS at the moment. The older style of SASS functions were a very limited form of macros. They're useful for a lot of things, like applying a generic button style to a bunch of different elements, but aren't able to, for example, make a standardized syntax for gradients which generates the appropriate code for FF/Webkit/IE. Previously to accomplish that sort of thing you'd have to use the Ruby API, as Compass does. Now you can do it entirely inside .sass files. This seems like a clear win, and will definitely simplify my stylesheets.