The ABP icon on my browser's toolbar has a tooltip that only says "AdBlock Plus;" regardless if it's a red or grayed out icon.
It would be incredibly much more useful if it could say "AsBlock Plus enabled" or "AdBlock Plus disabled" or "enabled for this web page", as it is not intuitive at all what the red or grey colors of the icon mean, it could be understood both ways, like red means ads are blocked, or red means warning, ads are not blocked.
Furthermore, when you click on the ABP icon, I still have no easy way to understand if the ads are blocked or not, because the same ambiguity remains, there is a slider that says "Block ads on (website)" with this time, a red/blue button, none of which explicitly tells if the ads are blocked or not. What would it cost to change the UI to something clearer, like with 2 lines, the first one saying "Ads are blocked" or "Ads are not blocked", and a second line that's just a single button "Block ads" or "Unblock ads" depending on the context. Why would anyone click on a "Block ads" button if they actually want to unblock ads? Did you catch the Microsoft virus, where users need to click on the Start button to shut down their computer?
Now, I know what the colors or the on/off slider button mean, but I am not a regular AdBlock Plus user, and it takes some effort each time to try to remember what this UI means or to try to understand it again. I think it should be much more explicit than the current poor UI choice. Just saying, because I really couldn't surrender a 10-star rating for this excellent app without searching hard for the slightest negative point I could find...