Probably one of the most under-appreciated (by public rating) Extensions on the entire Firefox Add-ons site. This Extension is one of the most powerful Add-ons any Firefox customization hacker could hope for. Unfortunately for them the source of that power is also the likely cause for the low rating, using its best features (hotkey initiated custom JS) requires extensive developer knowledge and testing time. Couple that with the incredibly unfriendly tiny UI Window (with hidden Save Button) and it is no wonder new users find difficulty & rate it low.

It seems like the "Run custom JS" feature is treated as an afterthought, but I wish the devs would extend it, for example: JQuery support; custom CSS/HTML/DOM; pass dynamic parameters to commands (ie: use JS to find a particular anchor or img.src then go to it in a new tab); Download/Save a resource by URL (option to bypass save-as dialog); would be awesome to be able to call a particular context menu item of an object on the page;

Currently I am using multiple add-ons to do most of what I need, but as I mentioned even without those dream features this is by far one of my favorite extensions available. HIGHLY RECOMMEND for those that know how to code.