It may not have been designed for audio files, but it's pretty damn good at them anyway - the hydrogen audio chaps rate is as equivalent to AAC and vorbis at the same bitrate, as well as having excellent quality at low bitrates along with low algorithmic delay. It appears to be a "cake and eat it" codec at present.
See here for their take on this very promising codec: http://wiki.hydrogenaudio.org/index.php?title=Opus
Now the problem that#s always plagued vorbis... will we see widespread hardware support for it? If it's already being deployed for Skype and WebRTC usage then I hope a few SoC manufacturers are going to support it.