I thought it's just me. I remember the first WaveNet demo sounded significantly more natural than the non-WaveNet stuff. But now they sounded almost the same. The main difference is that with WaveNet you don't hear that robotic tone at the end of a phrase, that's typical of old TTS technologies. But the way the phrase is spoken still sounds like a machine said it, rather than a human.

I wonder what compromises they made to improve the performance by 1,000x. There have to be some.