I used to be a big supporter of Sass, but now I prefer the simplicity of CSS. Look at almost any Sass project and it's usually overly complicated. I stopped writing Sass a few months ago and I haven't felt crippled at all.
The complexity of Sass/Less is starting to out-weigh the benefit of their features, for me at least.
That's on the individual project maintainer, though. Any valid CSS3 file is also a valid SCSS file, so you can add enhancements on top of that exactly as much as you want to.
The complexity of Sass/Less is starting to out-weigh the benefit of their features, for me at least.