The intellisense in the SCSS files are pretty weak currently; you get a list of possible keywords but that is where the support ends. It would be much more useful if the support was extended to the full CSS spectrum as per Visual Studio intellisense support. Examples (to name a few):
In the meantime I have to create a "sandbox" css file in order to build my styles and then copy/paste the result to my actual SCSS file. It would be much nicer to have only a single entry point for this.