For more information I'd recommend looking at their wiki.
At the moment the project is still in alpha. I've downloaded qTox to my mac and in terms of the interface everything seems to work ok-ish (there was some funkiness with the audio/video page under settings. Some of the buttons and icons come up pixelated as well but that's an issue I've found a good few applications have on the retina macs) but I haven't been able to properly try out actually using it for chat as I don't know anyone else using the protocol. I'm going to try get my girlfriend to install a client onto her computer this evening but maybe there would be interest in some kind of community here on Hubski for this sort of thing? The process of getting set up is explained here. I've created an id for the occasion if anyone wants to give this a whirl, it is:
565A4B0BDE727B612C2B985F66622786E3BFAED0E48BDCF46CC38ED2C084A91E4BCB71138991