Instruct: Classify an Amazon review into positive or negative sentiment.
Query: discovery 640 headset

the sound is very good. it's light and easy to use. it comes with several adapters for the charger, even one that works with my treo charger. that's a big plus. but it doesn't make up for the disappointing battery life. it lasts about a day. my previous headset was a plantronics 320. its battery lasted several days.