The update brings in high-quality voices. And as expected, the download sizes are much larger. The older versions were only around 5MB in size, now the high-quality voices are around 200MB or larger. Just for kicks, the UK Female voice is 276MB. So that’s quite the different, but that’s what high-quality does.
I use the Text-To-Speech feature a lot on my Android phones, in ebook readers like Moon+ Reader. It works really great to have the ebooks read out loud by the TTS feature. Excellent while driving to work for example. The voices has been quite natural, but with this huge update of the voices file sizes, must mean that the quality is now even better.
It will be interesting to try.