Fits well. People say my voice is muffled with ...
352279
Fits well.  People say my voice is muffled with this case vs naked phone.
638972
People have problems hearing me. I sound like talking from the barrel.
783584
Distorts sound, hard to hear and people say I sound like I am in a tunnel. Protects phone well.
4459032
Easy to take on and off (once you figure it out!), and usually stays in place.  However, if my ear is sweaty or oily (a lovely thought, I know), it tends to slide around my ear.  For the most part I had no problems hearing the other party and other people never had a problem hearing me.  Background noise from being inside a car didn't affect the quality of sound that was transmitted.
The biggest problem I found was that most people I talked to complained that they heard their own voice echoed back at them.  This was not something that I could hear on my end but I verified it when I had someone call me using this headset.  This is *very* annoying for the person being called.
1153174
Will protect your phone very well, but it also makes it soundproof also.  You will be able to hear the other person well enough, but the person you are calling will tell you that you sound very muffled.  Switched to an Otterbox Defender, now my friends can hear me.
3728354
This phone case disrupted my calls. Everyone said that I sounded like I was muffled
4950995
Great for the radio but people have a hard time hearing me when using the phone. I have even tried to bend down and talk directly into it.
3838339
Sound quality, voice quality is great.  Fit, not so much. I think I have an average sized head and these fit tight.  I've tried stretching the headband for a less tight fit, but they are constructed well so I haven't been able to.  If you have glasses, remember that these are tight.
4704267
This is a good headset.  You can hear the other party very well and it fits snugly into the ear.  However the receiving end sounds a bit muffled.  Haven't found a way to adjust that.  Otherwise for the cost, a solid product.
1529337
It would be lovely and perfect for the price, but when I call people, they tell me my voice is not clear.  The case that holds my phone seems to muffle my voice. Plastic material too thick?
1281282
The case is good.  Fits well, screen functions are not hindered, etc.  The problem?  Absolutely no one can hear me speak, and if they do, sounds like a towel is wrapped around the speaker.  I have to take the case off EVERY time i want to use the phone.  Replaced it with a Otterbox Defender, while it is much thicker, people can actually hear me.
639364
Microphone works pretty well, but gets drowned out by surrounding noises easily. Almost has to be silent in the vehicle for anyone to understand you. Still much better than the microphone that my head unit came with. Multiple mounting options to boot. Overall, I recommend this!
4486306
People can hear me and say the sound is relatively clear. Voice codecs on teamspeak or variants may muddle the quality, but uncompressed it's ok.
4199613
I am often told by people I am speaking to that I sound like I'm under water.  It is the worst when speaking to another bluetooth user.
3371472
I really like this case, its got a good structure and my phone does feel secure in it. The only problem and the reason I cannot use it any more is the mic/speaker area for callers to hear me is covered up some. It muffles my voice a lot (I am a soft spoken sort of person) where the caller can't hear me.
2040138
This headset fits well and the sound is good.  However, the microphone doesn't allow me to talk if someone else is already talking.  This is extremely annoying.

I would not buy this headset again.
144373
When I talk on the phone, people complain that they cannot hear me. Also, I couldn't fit my charger cable in the slot. It seems waterproof.