I love these headsets.
It's as simple as that. They are amazing at what they do, there is nothing I can say against them.
I usually use mine for voice communication over the internet, however more and more I have been using them as a general pair of headphones for listening to music without interrupting anyone else - and they are surprisingly clear, easily as high quality as headphones that are designed simply as headphones.
The microphone is also of excellent quality, it is very, very rare that I receive requests to adjust my microphone when talking with people and the only problems that I have experienced are that the background noise blocking can sometimes block out your voice ever so slightly, but this is rare and doesn't cause too much of a distraction as long as you are speaking clearly.
My advice for consumers looking for a high quality headset would be to find one of these online, they are rather cheap now-a-days as they are older products - although I whole-heartedly consider them to be better than the newer versions, even the newer versions made by Logitech.
Also, the fact that they connect via the USB port is excellent, it makes the sound a lot clearer and allows you to add a second mic to the mic jack if you desire. Additionally if your mic jack breaks most computers do not have another one, whereas if your usb hub breaks you can simply use one of the other ones.
One last point that I'd like to mention, the headset is extremely comfortable and barely noticeable even after hours of use - this is compared with most headsets that either have a ridiculously amount of padding that squeezes your head together, or solid plastic ones that cut into the tops of your ears!
I've been using these headsets for quite a few years. I have tried many other headsets, including newer Logitech ones but find myself always coming back to this. Mainly due to the other headsets not being compatible or having poor microphone quality.
I generally use headsets for 4 things, they are: Listening to music, watching things, audio on Skype and voice communication in video games.
When listening to music I find the headphones to be quite comfy, the ear pieces themselves are black leatherette and slightly padded - not overly padded to the point where it feels uncomfortable or too big for the ear. Due to the comfort of these headphones I'm able to wear them for at least 2 hours without feeling any discomfort. The headband is also adjustable so you can get the perfect fit. The quality of the sound is crystal clear, when listening to CDs my music sounds perfect quality without any faults or problems. When watching things such as DVDs I also find the quality of the audio to be perfect, I'm able to watch in comfort without having difficulties of hearing the film. If you're looking for advanced sound quality then these aren't for you, I definitely think they are made more for general listening.
When I'm using this headset for Skype I'm able to hear the other person very clearly, to the point were I don't need the volume turned up very loudly. However they can hear me quite well but sometimes say I sound a little low. I have yet to figure out why this happens, it occurs randomly but not very frequent. The microphone also blocks out background noise very well and static, the only static it usually picks up on is noises caused by myself, for example if I scratch my head it may sound like static as its close to the microphone. Overall the microphone quality is good.
Voice communication in video games is also very similar to the quality on Skype, however due to the sound effects in the game sometimes fellow gamers may find it difficult to hear me but not all the time. I generally can hear them very clearly unless they have a weak microphone themselves. Again the sound effects in the video games I play sound very clear.
These headsets are USB, once you've plugged them in they work, very easy and straight forward to set up - no hassle. I find these headsets can break quite easily if they aren't taken care of, they can be quite fragile. I have found myself breaking a few in the past easily due to accidentally sitting on them or them falling on the floor.
The availability of these headsets is getting harder to find due to the age of them. I usually order mine online at an average price of £20 as they aren't available in stores any more. I will continue to use these headsets until I'm able to find a good replacement at an affordable price that is compatible for both Windows and Mac.
These USB headphones are loud, clear and comfortable. I use them for Skype on my laptop and they are ideally suited. The microphone is quite clear for other users to hear at their end, and the in-line volume control makes it easy to adjust for over-loud calls (there's no volume control in Skype!) The driver software was easy to install and, because of the USB interface, the headphones automatically show up as an option in 'Sounds and Audio Devices' within Windows, which means you can easily select them for any program on your PC (or, indeed, on your Mac). Apart from Skype duties, I have recently been using these to listen to audio and DVDs, and have noticed an even response across the full frequency range, which allows good playback for all those bass-heavy DVD effects. I strongly recommend these headphones.