We paired the Samsung WEP870 with the Apple iPhone 3G. The pairing process went smoothly; we didn't even need to enter the PIN code, though this might depend on your phone. We were quite pleased with the call quality on the whole. On our end, we heard our callers loud and clear, with a little bit of static here and there, but nothing distracting. Voice quality was good and natural as well.
On their end, callers said they could hear just fine, too. They did say our voice sounded a bit hollow with a slight echo, but the overall call quality was good. When we had the stereo earbud lanyard attachment connected to the headset, callers said they heard slightly more static. We also tested the WEP870 in a moving vehicle and in a crowded restaurant, and it did a decent job of canceling out background noise. Callers could hear some environmental noise, but not much. Still, we wouldn't use the WEP870 in a windy environment; the wind muffles the calls too much.
As for audio playback, we found the sound quality to be very good. The stereo earbuds provided rich and warm audio, though bass was still a bit on the light side.
The Samsung WEP870 has a rated battery life of 6 hours talk time or 6 hours music playback time. It has a rated standby time of 6.25 days.