Instruct: Classify a given review as either positive or negative.
Query: Cool headset with great quality

Similar to most other reviews, I find the 645 to be very effective. Quality is good both ways as long as you stay within 20 feet of the phone. I use it in the car all the time and no complaints. Battery life is decent and great with the battery charger handy. I wish it would stay in the cradle a bit better though as sometimes it just falls off while walking or climbing stairs.