@Madmax ... "Flashing screen..." Rated 5 out of 5 stars

This add on, by it's self, does absolutely nothing... It needs another ingredient in order for it to effect your browsing experience... If your browser, screen, keyboard, webcam, or anything else is, in fact, "flashing" you may want to take a better look at whats going on in your FF installation... I digress...
Anyhoo...
As long as you stay updated and keep up on the happenings in greasemonkey and greasefire land you should be good to go. Occasionally, there will be a minor incapability that will break the functionality of a script or Mozilla will change something inside FF that causes GM to go a bit haywire but they are quick to patch or declare a permanent change in the scripting language that causes certain scripts to no longer work on their end. Just read up on the FAQ's and stay away from spammy scripts, and you can greatly increase the functionality of FF. enjoy!

This review is for a previous version of the add-on (0.9.20).