Apple's change in voice talent is an improvement though, and they may have more units than before, which is helpful. I believe their model also works offline, which is a huge plus (though I think Google's prior model works offline as well).
I learned a useful new word, thank you!
There are noticeable blips in the speech that sound unnatural, particularly when certain sound combinations are used.
The very first sample with "Bruce Frederick" is clearly off. The intonation and timing between the end of bruce and the beginning of frederick is... mechanical.
There's a similar problem in the OPs link with the non-wavenet English voice 1 when it says "Wavenet".
Those issues are much less apparent in the wavenet voices. Timing problems are less noticeable, intonation problems are less noticeable.
Frankly, the voices there sound VERY good, compared to anything I've heard.
That said, I completely agree that there's not enough samples there to make any real judgement.
Still, they picked one that makes theirs look vastly superior.