Yep. It blocks the Like buttons and other stupid widgets, which is how the cookies get sent. That also has the pleasant side-effect of drastically decreasing load times.
I highly recommend it. Be aware that it does block disqus by default, I usually whitelist that one.
I had a few problems with the blocking when actually going to the sites in question. I believe I had to unblock Google Plus, Google Analytics and Facebook when actually visiting those sites.
However, I'm happy that most of the time it prevents the annoying features of a page from loading.
Yes. Ghostery is much more targeted however, it blocks scripts based on a blacklist (of trackers) rather than blocking ALL scripts. Ghostery is much more user/non-techie friendly; the only time you need to mess with it is:
a) You want to allow some service (I allow disqus, for example): disable blocking for the service
b) A site requires facebook/twitter to log in, or you trust the site: whitelist the site (allows all tracking scripts)
I do wish it had a "allow by domain" so I could allow e.g. just facebook on just turntable.fm so I can log in, but not allow all of ttfn's other trackers.
I highly recommend it. Be aware that it does block disqus by default, I usually whitelist that one.