It's a pleasant sound, but - as other people have noted - intelligibility can be low.

The Emvoices seem to work well when the syllable rate is fairly slow.

They also have a glassy, over-processed tone, so they work much better with a production that uses that sort of tone.

With the progress of vocal synthesis and neural networks, we're rapidly approaching the point where synthetic voices is virtually turnkey. I expect to see a lot more high-quality synthetic singing programs in the near future.

-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?