Sweet ANN is a Vocaloid 2. That tells you something about the skill of the person who put together this demo.

Here's a demo I did using Avanna, which is a Vocaloid 3. The backing is BiaB, and I didn't do anything special to the vocal: The Water Is Wide

I think it's a good example of the sort of results you can expect from a Vocaloid.

Vocaloids can be used to create some very appealing vocals, but even with the improvements of Vocaloid 5, nothing that will be confused with an actual human singer.

If you've got the money to spend, go ahead purchase a Vocaloid to play with. They're a cool technology.

But if your English is fairly good, even if you're not a strong singer, you'll get better results either singing yourself, or getting a friend to do it, and pitch correcting the results if necessary. Or - as suggested - find an inexpensive singer online.

Either way, the results will be much better than with a Vocaloid.

-- David Cuny
My virtual singer development blog

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