Pro Allows screenshots (either the full page or parts of it) if performing UI testing
There are times where you don't want to open up a browser for screencaps, that is where CasperJS comes to use, it can render the page using its own rendering engine and take and save a screenshot for you, all via the commandline
Con Cannot guarantee 100% accurate Webkit-based browser screenshots
QtWebKit is the rendering engine used by CasperJS. Keep in mind this is not the same rendering engine as Chrome; hence, if you want to be 100% sure of the results, you must run a Webkit browser (such as Chrome) yourself.