Seems like a cool, simple web app. The voice isn't great though. I would think that it's pretty easy to have a nicer computer generated voice nowadays, but I've never built something that needed to do text to speech so maybe not.
Author of the app here: The voice is whatever your browser on your device uses by default for speech synthesis. E.g. on an iPhone it may be Siri's default, on other platforms it is a different voice.
Are you checking for spoken article coverage? There are not a lot, sadly, but some places are covered.