Excellent! Very good sound, I can hear and be heard very clearly, just like I read in the comments. They are extremely lightweight and do not tire me out, I use them for several hours a day. They replaced my heavier headphones that I used to accompany with a microphone. They are also amazing for travel (for connection with a computer), as they are a decent weightless solution.

Very good for multimedia headsets and for their price. Sound and microphone quality are ideal for teleconferences. They are very lightweight and don't tire you out, but they have a thin cable and a frame that seems fragile. However, only time will tell. Noise isolation is not good, but we are talking about multimedia headsets, so I don't have high expectations. Overall, I am quite satisfied.

Update after some time of use: I don't know if it's because of the specific piece I got, but I have encountered the following two issues. Firstly, sometimes when I can talk normally for a while, suddenly the sound of my conversation partner becomes distorted and I have to reconnect the headset to fix it. Secondly, sometimes my conversation partners complain about hearing strong interference without having any other device nearby (e.g. mobile phone). Unfortunately, I am not satisfied and I will prefer to choose a different pair of headphones.

I ordered these from abroad about two months ago. For those who are familiar, Sennheiser is one of the top companies in the field of headphones. I got them for telecommuting due to work and I use them on a daily basis for 8 hours.

Positives:

They are incredibly lightweight, so they don't tire you out even with all-day use.

The microphone they have is one of the best I have personally worked with, based on my experience with multimedia headsets. You can hear and be heard very clearly.

Additionally, their connectivity via USB port is extremely easy without any issues (Plug n Play).

The noise cancellation is incredible (10/10).

Negatives:

Because they are very lightweight, they appear to be of cheap construction compared to some other brands, but personally, I don't mind that as they are quite comfortable to use and, as someone mentioned before, you feel like you're not wearing them.

The cable they have is quite thin and not as durable as in some other headphones, which concerns me regarding their lifespan in the future.

Their bass is quite average, but it is understandable since they are multimedia headsets designed for this purpose.

Their sound isolation is quite average, but it also depends on the work environment you are in.

Overall, I consider them to be a very decent purchase that you can find within this budget. There are lower-cost headphones available, but personally, I believe that Sennheiser equals quality.

I should note that these headphones do not meet the needs of gamers and are only suitable for telecommuting and computer use. So forget about the sound isolation or bass if you are interested in this use.

Sennheiser is a reputable company that produces professional audio products and high-quality hi-fi. I have had this specific headset since the first lockdown and it is amazing for teleconferences on Webex, Teams, Skype, and obviously Zoom, Viber, Messenger, etc. on a PC or laptop. Now (11/2020) I also bought a second one for my partner who is a teacher, and she is thrilled with the sound quality and how it doesn't tire her during long hours of work (compared to the €19 headset she used before, or compared to mobile headphones). The conversation with this headset has a natural sound quality, as if you are in the same room as the person you are talking to. You can hear and be heard clearly, loudly, and without tiring or unnecessary frequencies. It performs exceptionally well in music listening, but it is not intended for that. In general, when a headset is specifically designed by the manufacturer for conferences, it will not play music perfectly - and vice versa. In teleworking, the needs are different: comfort during long hours of use, clear sound with emphasis on human voice frequencies and NOT on bass, noise cancellation so that you can be heard well without echoes from walls or household noises, etc. The Sennheiser excels in all of these aspects. Compared to the Logitech h340, they have clearly superior sound quality, but they lose in terms of build quality (the h340 looks more sturdy). The build quality initially seems average because they are very lightweight, but they are more than OK for €35. They are so comfortable that you can hardly feel them, and they do not tire the ears at all. The cable is conveniently long (2m), it is thin but appears to be good and durable, it has a mute switch for the microphone, and volume control for the headphones. The microphone can be adjusted and you can even twist it without the other person hearing any scratching noises. It is plug-n-play on Windows 10 (no drivers needed), and they connect via USB in mono. Excellent.

*Edit* Since I am professionally involved in music and sound, many friends and colleagues ask me things that it is better to clarify here.

Noise cancellation: This technology works when you are speaking, not when your microphone is open and you are simply listening to others. Essentially, while you are speaking, the sound of your voice is transmitted without the surrounding noise. When you are not speaking in a meeting, it transmits all the sounds, and you MUST activate mute (either from the PC or from the headset switch, which is why headsets have mute buttons). If you are in a noisy environment with an open microphone and you are not speaking, it will transmit all the noise. This applies regardless of the headset brand, and unfortunately, many people judge headphones negatively because they do not know how to use them correctly in chats and meetings. In this specific headset, the noise cancellation works exceptionally well (isolation of YOUR VOICE from the other noises in YOUR SPACE when you speak). If you need them for a very noisy environment (such as intense music in a bar), then the situation is not salvageable anyway and you have to pay a lot of money for specialized headsets.

Sound isolation from the headphones: These headphones are small, lightweight, and rest gently on the ear, they do not envelop it (like studio or gaming headsets), and therefore they do not isolate the space 100%. If you are interested in work and not gaming, DO NOT go for gaming headphones or over-the-ear hi-fi types because after a 2-hour meeting, your ears will be burning and your head will be a kettle. Especially gaming headsets are designed to isolate you from the environment and accurately reproduce a space (such as the arena of a game, for example), often creating echo, with a negative impact on how you hear a meeting with 6 people. Personally, I don't mind being able to hear the doorbell if the delivery person knocks on it, without that meaning that I hear the noise of the house. As I said, these specific headsets are the best for remote work.

If you want to play games with Dolby, etc., get a gaming headset for €150. If you have a golden ear and want to listen to Mozart, you need over-the-ear headphones for €300. If you record or mix drums and electric guitars, you need neutral studio headphones. These specific ones are for video calls and are judged as such. I don't think there's a reason for someone to spend more money for such use, and Sennheiser is a top choice. The idea of spending a little more to listen to music a little better or to play games, etc., is a misconception and not true. The only reason I can understand for someone to spend more is if they want wireless headphones (personally, they don't work for me because they are much heavier, and it's a matter of time for the battery to run out in the middle of a meeting).