Rated 2 out of 5 stars

nice idea actually, but it almost never works. e.g. the addon always sends one "http://" too much to "webarchive", so that you have to correct it manually.

This review is for a previous version of the add-on (1.9m1.1-signed.1-signed). 

Sorry. It is WebArchive site problem. They changed URL syntax. I fixed it now in Web Cache View Plus 1.9m2 version.

Just wait the acception of new version by mozilla or you can try
https://addons.mozilla.org/firefox/downloads/file/183624/web_cache_view_plus-1.9m2-fx.xpi?src=devhub
but this link can not work.