Weird that no one here is talking about voice quality, which was what stood out to me as most interesting about the product. I've wondered for a while why, if we can handle something as high-bandwidth as video chat, we can't do higher-fidelity audio chat over data.
But I just tried it and it sounded more or less the same as a normal cell voice call. Also the UI is pretty but slow-feeling on Android. I have a feeling it's smoother on iOS. Disappointing.