Once installed, if you find a long text you want to read perfectly, use the icon next to the search box or the assigned hotkey. When you do it, the selected text will be highlighted and the rest of the screen will get dark. By this way, you'll read it better. It will seem a PDF file. The font will get a bit bigger, you'll welcome it.
Furthermore, you'll be able to share the text in Facebook, Twitter, print it or send it via email. In short, if you usually read news and long posts, iReader will be really useful.