When I first started using text to speech, I had difficulty understanding it. Whole sentences would disappear into an unintelligible mess. But then I learned to understand it, I suppose it's like your brain adapting to understand a strong accent. Now, I can listen to books without a problem, even at full speed. I find the female voice works best.
Audio books read by a human are better, of course, but I find text to speech meets my needs now that I have adapted to it. TTS is always available, even if I haven't downloaded a proper audio book.