I have one, love it. You can talk on the phone, carry on a conversation without yelling, and the women love it because it doesn't blow their hair nearly as much. It also makes top down season last longer since there is less air blowing on you to make you feel cold.
I agree with Nate, the only downside is the backseat is not usable, but it removes and installs in seconds, so it's not a big deal.