Excellent (until update) Rated 5 out of 5 stars
So useful that it is downright painful to use browsers without something like this installed.
It does get annoying when Firefox updates and it complains about AiO being incompatible. I just updated to FF8 myself, and AiO worked fine until the next session when Firefox actually checked add-on compatibility. (Most AiO updates these days are just to slap on new version numbers in its config file! You can get by with a little tinkering in its install.rdf file.)