What makes it so awesome is really the way it handles concurrency and automagically synching a bunch of different "shreds" at the same time. Its deeper than say the web audio api. Where it is lacking is in mobile support. The ancient Csound has an android version that actually enables you to develop the live code on your android device. While with Smule you had a cool adaptation for ios, Csound still seems to be more forward thinking in that it already supports android and chromeos.