Positives:
- Idiot-proof, works out the box
- Novice and expert mode
- Listens and responds to community
- Beautifully designed interface
- Massive blocking list.

Negatives:
- First install: 'Analytics and "Human Web Data"' is actually opt out which is predatory for new users.
- Smart filter allows certain ads and tracking sites (Google ads for example).
- Owned by Cliqz GmbH who profit off anonymized data collection. They have to play nice with competing advertisers and trackers.
- Proprietary closed source/ partially open source.

I suggest using these addons who have no ties to user data collection/advertising as of now:

Ublock: Blocks ads / trackers
Umatrix: Allow/deny third party elements
Cookie Auto Delete: Keep useful cookies, auto delete trash cookies.
Privacy Badger: Uses heuristic for trackers, a "light" open-source variation of Ghostery.

As good as it is, I ended up having to disable it because it was causing some incessant problems on many of the sites I frequently visit. To start with, it always blocks Disqus, a comment system frequently used all over the net and although blocking of Disqus can be disabled, even after doing that, I'm still unable to log in to DIsqus unless I completely pause Ghostery, log in, then unpause it. Even then, when I unpause Ghostery and I reload the page, I find that I've been logged out of Disqus, yet this doesn't happen when I keep Ghostery paused. It also frequently causes problems on a bunch of different websites, such as blocking captchas, making it impossible to do certain things like log into some sites or create accounts on others. I could go on and on, but long story short, it caused me too many problems than it solved, so I'll be keeping it disabled until it gets a few patches

Good

Cela fait un moment que j'utilise Ghostery mais depuis les dernières versions (1 mois environ) j'ai des problèmes avec des sites (paiement en ligne rejeté, perte de session). Un site me dit que je n'accepte pas les cookies alors que je n'ai pas ce genre de blocage. Un autre me dit que je bloque ses pubs alors que dans la conf j'accepte tous les mouchards... Pour que cela fonctionne il faut que je désactive Ghostery.
Dommage mais espérons que cela n'est qu'un bug temporaire...

Good but I didn't understand well how does it works on the mobile version, it is really different from the PC's screenshots! So I don't know how to use all the potential of this extension!( Specially in Waterfox because in Firefox nightly it isn't so bad as the "ghostery option" in the "3 dots" still working here but not works in waterfox