I considered one but I live in the south and that cold air blasting the phone and then stepping out into our high humidity didn't seem like a good thing. We have a month and a half yearly where if you are in the car for 20 minutes or more your eye glasses are going to fog over as soon as you step out.
Also, unless you are a gecko you are likely taking your eyes off the road to look, you just don't have to go as far to look.