It's amazing, mate. Sure, reading books for the sake of reading at your own pace is great; however, for the boring shitt you don't want to spend your time reading? Just use this!
There's a chrome extension version for the above example called 'Readline'
There are many ways to use it. For me personally, I highlight the text that I want to read and hit the space bar, but you can set it so it opens up once you've highlighted the text...perfect for block of text etc...