The language has more powerful functions available, or at least it did when I first compared them.

I also find Compass, Bourbon and Susy to be great assets.

The Chrome dev tools support is outstanding.

The biggest drawback is that there's no client side evaluation like less.js. This occasionally makes working with other people a bit tricky. I usually make a sandbox.css for them to fiddle with, and then incorporate their changes every so often.