I'm a skilled PC user, but this add-on has helped save me from accidentally opening scam/imposter websites several times. Since adding it to Firefox, my SUPERAntiSpyware scans have also picked up way, way less PUPs and trackers to clean! It's definitely effective and I consider this to be a vital add on to get whenever I've had to reset a device or use a new one.
The only problem I have with it is that it has no accessible whitelist option. You have to go into your browser's add-on settings and completely disable it if you ever find that it's blocking an important popup. Though that's rare and it's still more than worth the benefits.
