It'd be a lot more useful if it worked on connection failures (as such no HTTP errors).

It also doesn't work when the webserver redirects to some other page (an in-wesite error page or something else) without throwing a http error. Limiting it's use even more.

Even worse it doesn't seem to work on all 404 errored pages that I tried:
http://mkw.mortalkombatonline.com/games/mkt/