As far as it goes, the AAA Foundation for Traffic Safety's study on the dangers of using hands-free devices while driving is accurate.
However, it should be noted that the hands-free technology in modern cars is new and that in time drivers will adapt to these systems and will learn how to manage all this new information. We are only in the infancy of this pervasive technology, and it's impossible to fully understand how we'll adapt to it in the future.
The study on distracted driving hit home for me.
A few years ago I was given a little nudge about talking hands-free while driving. I missed my exit—twice. It was the second miss that told me this isn't working.