This is a great ad blocker. It works perfectly and I've never had any problems with it.

Slows firefox...

Super

Does the job and does it well.
Been using it for a very long time.
I wish it updated the filter lists more often though, like daily.
Also hope the work continues on improving it.
Particularly on it's performance

so far so good.

When it works, it works. Unfortunately it's missing crucial features, like

- undoing latest blocking action.
- listing ALL manually added filters (only shows a few dozen and then the list cuts off).
- search function for "Add Your Own Filters" in order to remove an item from the list you accidentally blocked, which means you need to completely reset the addon and start from the very beginning.
- keeps redownloading foreign language filters that I've disabled AND deleted. It's annoying.
- the Adblocker menu stays open when you click "Block Element" (whereas it should disappear automatically), and blocking box is often hindered by the annoying Selection Mode popup.

I've reported these before to the support email but was ignored. Doesn't really encourage me to donate when maker is oblivious to feedback.