Good listening to music - call goes like this.

Sound:
I know of no comparisons in this price range but I can say that I am satisfied with the sound. Of course you have to be aware that there are no in-ear headphones, you thus to an even heard Umweldgeräusche what I find on the road very well, on the other hand in quieter environment and loud music and sound penetrates to the outside, so the environment can listen.
* Edit: I've been through a little play around on my phone Equalizer found that the headphones still länsgt was not on the limit and even brought out a lot. Now am no longer satisfied but even thrilled, now what moves me from originally. 4 stars to 5, with an exception for the batteries.

Ergonomics:
The MM100 is nice and light, not pressed for long-lasting, it is super comfortable and in winter even the ears warm. It sits firmly enough so that it is also suitable for jogging. The skip buttons as well as the +/- buttons are well placed and easy to use. Only the Allzwegtaste on / off / play / pause / answer / end call etc. has no tactile feedback and is thus not entirely succeeded.

Bluetooth, operation and telephony:
The Bluetooth pairing with my Samsung Galaxy S2 was smooth. There are several beep and flashing light-Vairanten that indicate different status. Somewhat confusingly, the most important one knows but quite fast. The telephony I see as a bonus, thus falls not as strong in assessing the weight. In closed rooms in quiet environments, the microphone is to use very well. It sounds as if you've put the phone on speaker. Outdoors and in a noisy environment is, however, quite difficult to understand. There are several operating options for telephony as reject a call or mute micro etc. This is NiceToHave, to me, however, especially since I use a bit much to MM100 less for telephony.

Battery and power:
Sennheiser used here unfortunately no MicroUSB port, but its own solution. Big minus for that. The supplied Sennheiser charger is connected via USB to the least annoying blue glowing power supply, so you can load it after all, also on PC. The battery life, I can not hardly measure. So far I am satisfied. However, I'm curious on the life and whether or how you can then replace the battery. If necessary, I edit again later here.

Conclusion:
++ Sound; ++ Ergonomics; +/- Telephony; Type charger; (+) Battery -> Since mainly bought for listening to music 5 star, with an exception for the batteries.