Personally, I'd prefer to read the text and would not use the feature. However it does add something to the atmosphere, and may indeed make it possible for visually impaired players to enjoy your game, though it's no substitute for a human VA. Some of the lines have suitable delivery by the AI, but that "omg" at 2:14 is... lacking.
The quality of the generated speech is quite impressive, I must admit. It reminds me a little bit of the voices in some anime where the voice actors weren't always native English speakers and it would show in their performances. I've only used a speech synthesizer for the voice of a spacecraft's computer in my games myself, but I could also see uses for AI speech as placeholders for timing purposes, or while the dialogue hasn't been locked down, until the lines can be recorded by real actors.