Well, I figure that seeing the words is easier than just hearing the computer talk, right? At least the input is visual instead of aural.
I'm a visual learner, though not visual-spatial. Seeing the words certainly helps me, and it seems to help DS8.
DS8 has done nearly all of the 3 Plato Science programs. (One expired before the end of our year, and we were close enough to done, that I didn't renew it.) He really likes them, and it's something that he can mostly do by himself now. (Not so much at the start of last year, when he was just barely 7yo, but now it's no problem.) It has turned him on to chemistry in a big way!
I like Plato because it is very visual, but it's also nicely interactive. The kids do things like diagnose what's wrong with a cell using a machine that tells them the cells symptoms. Then the child has to say that the mitochondria is not working, for example.
And the content really seems geared to the 7-9yo HG+ kid without talking down to them. The material is challenging. DS8 rarely gets 100% on the tests, which I LOVE! He's actually having to work at it! And he remembers the material. It sticks!
I don't love the time slots. That's a fairly recent development. It's a limitation. But it's a good product and I give it my highest recommendation, especially for visual learners.