Feel free to post here with your experiences on BBM Voice!
I just made a call and the call quality is quite good. If both parties talk at once it does appear to drop one of the voices though.
To answer or hang up, it seems like you have to use your physical buttons; it would be nice just to tap the person's avatar to answer a call.
I turned off my cell network and just used wifi, and as expected it worked flawlessly! I got my brother to turn off his cell radio too ( so we were both just on wifi), and we talked over long distance with no problems! This is definitely a great feature :D