It is still pretty new, yes, but it seems to work well (see for example https://hacks.mozilla.org/2014/10/unity-games-in-webgl-owlchemy-labs-conversion-of-aaaaa

It is still pretty new, yes, but it seems to work well (see for example https://hacks.mozilla.org/2014/10/unity-games-in-webgl-owlchemy-labs-conversion-of-aaaaa-to-asm-js/ https://hacks.mozilla.org/2014/10/unity-games-in-webgl-owlch... ), and it's been one of the most-asked for features by Unity users on their forums.