The Sennheiser MM50 iP, Sennheiser's new iPhone headset, delivers excellent quality audio and hosts a push-to-talk microphone that, though bigger than some, is sensibly made so you can intuitively switch to take or make a call.
We were impressed by the Sennheiser MM50 iP's audio quality - certainly, they're equal to any other set of iPhone-focused headphones we've seen, and at a pretty decent price too. They have a strong bass response, which pleased us because so many headphones deliver excellent sound everywhere bar the bass. Distortion is also very low - you really have to max out the volume to get playback problems.
Despite being in-ear headphones, we were a little disappointed at the Sennheiser MM50 iP's noise isolation capabilities. We don't think the seal between the earbud and the ear canal is particularly strong, meaning we experienced more sound from the outside world than we expected - but some may consider that an advantage, as it means you can keep half an ear on what's going on around you.
We have one more minor gripe. While the Sennheiser MM50 iP's cables are light, their featherweight rubber cladding makes it too easy to end up in a tangled mess. You have to be conscious of how you handle them, and can't simply stuff them carelessly into your pocket.
The Sennheiser MM50 iP headset delivers impressive sound quality and the design of the push-to-talk mechanism, while bulky in comparison to some alternatives, makes that feature easy to use. The cables are subject to tangling and the sound isolation isn't the best, but for the price these remain a worthwhile investment for most iPhone users.