Works great for me. Calling, asking a direction or searching for a song are working great for me. My car is setup in French. It is so brilliant that I can mix the French command with a English song name. This is compared to the unusable -for me- Audi system in my previous A4.
I do reckon that if 3G coverage is weak or plain not there, voice commands do not work. Which is expected for a online system.