My Dota 2 works pretty fine on Mac except for two things:

1- Sudden crashes (I expect this to be fixed soon anyway)

2- Sometimes in-game voice not recognising the voice input.

I can sometimes get my voice across, but after a while Dota 2 will not recognise my speaking. I can fix this by leaving the game and reconnecting, but again the functional in-game voice will last only for a while before it stops working again.