The sound quality on the Sennheiser MM50 is crisp and clear. You can hear even the subtle sounds that add real depth to your music.The ear pieces fit comfortably in the ear. With the three different sizes provided, it's easy to find the one that fits best.The call quality is great as well. The people I called said I was coming through loud and clear. The inline microphone could use a little more cable length between the mic and the earpiece on the left side. If not clipped up high on your collar it can pull a little as you turn your head. It's not really a big deal though.The system works well with my Blackberry 8830. The 90 degree connector fits and works well, even while the holster.I have even used this while cutting the lawn. The design of the earpiece did a good job of blocking the noise, and providing a good listening experience. I don't think you will be disappointed.