Just installed this and it does a good job of blocking ads and trackers. However, there's a bit of a bug on some news sites when using Firefox. When I go to read some articles, the scrollbar is missing and I'm also unable to read by paging down. Pausing restores the scrollbar and it doesn't go away when re-enabled. I've had this happen on CNN.com several times.
Also, as long as you're blocking annoyances, can you please do something about those autoplaying thumbnail videos? They're every bit as pesky as ads.