Excellent in all aspects. Fast response, properly adjusted key travel, very functional distribution of additional keys on the keyboard surface, low typing noise (except for intense moments in gaming), zero connection interruptions, sturdy and elegant construction, sufficiently stable on the desk surface.
Very good quality of the casing and plastic parts. Satisfactory range of lighting settings (colors and intensity).
It is certainly very expensive, but if you plan to use it for 10-12 hours daily, it will show its value and durability. It is categorized as gaming, but I believe it also excels in text-intensive tasks, coding, or audiovisual applications (Lightroom, Premiere Pro, DaVinci, etc). The layout DOES NOT include a numeric keypad, but I don't think this is a problem for those who don't primarily use Excel or applications with a heavy load of numerical typing. Also, the keys are not engraved with Greek characters.
I haven't had the chance to spill water, coffee, orange juice, etc. on it yet, but the keys can be easily removed and cleaned without much hassle.
I highly recommend it for users who have the financial means to acquire it and spend many hours daily in front of a keyboard.

For someone like me who can't stand cables, I can say that it is excellent and has nothing to envy from wired gaming keyboards. Its response is incredible and the keys have a wonderful feel. I bought it about 6 months ago and I have never felt restricted by the charging and there has been no disconnection whatsoever. Yes, it has a micro USB for charging, but the cable it comes with is long enough to have it behind the PC and only pull it when it needs charging.

Another good thing is that for someone like me who is not very knowledgeable and is a bit afraid of these things, removing the keys to clean them from the dirt they have collected was a piece of cake, without needing a special tool. I did it by hand, fearlessly, without worrying that I would damage such an expensive keyboard. The same goes for reassembling it.
IMPORTANT: If you are going to remove them, take a photo before, because then good luck finding where each key goes.

Regarding the cons, I have to say that I also face the issue with the F1 key, which whenever it gets stuck, it stays in yellow regardless of the profile I have set. I should mention that if it gets stuck in yellow and I press it once, it returns to the color I have assigned to it. It's not a solution, especially for a keyboard that costs 250€ (I got it for 190€ back then), hence the 4 stars, but at least it doesn't drive me crazy when a key is a different color.

P.S. To fix the F1 issue, I use the echo profile from the Logitech application. I mention it because you might need to have a profile where the RGB reacts to key presses instead of changing on their own periodically.

The keyboard is a masterpiece in terms of construction quality and key feel.
I was very skeptical before buying it because it is VERY EXPENSIVE, and definitely not for everyone's budget.
But since I have used many keyboards in my hands, and I was looking for a 6-month change from a motospeed with blue switches, which tired me both in feel and noise, I decided to make the leap and spend six times more than what I was used to spending on keyboards.

I also took the risk of going for a TKL and wireless.
The lack of a numpad only costs me when typing codes and IPs, which doesn't happen very often, so we're good, I didn't expect it to be convenient, and the smaller size is actually very convenient for easier mouse movement.

The wireless is just a pleasant little comfort, since I don't move it, but let it be.
The battery lasts a very long time, even with extended use.

The lighting is good, but unfortunately the keys with extra characters are not illuminated on the extra characters...
Another positive is the volume control wheel, but I would have liked it to have some feedback and more resistance.

Also, the biggest negative is that it doesn't have USB Type-C but the older one...

I have the brown tactile white version. I use it for typing and programming. For me, typing quality is of utmost importance. And I wanted a low-profile keyboard because I type for over 8 hours continuously, and low profiles are better for the wrist.

Observations:

- The white keyboard is very good for seeing the keys without needing backlighting. However, the LEDs are better in black. Personally, I prefer the white one. It allows me to turn off the LEDs and save battery.
- The best Bluetooth and the most responsive. There is no better, I have tried others.
- It has 3 connection methods: cable, Bluetooth, and lightspeed, which has a USB dongle - an amazing feature that can be stored in a special compartment under the keyboard and not be bothersome.
- Incredible build quality. Aluminum, no metallic noise. It is the heaviest keyboard I have (heavier than the Keychron K1).
- Keycaps "float" a bit, but it is not noticeable during typing. Note that you cannot find replacement keycaps - low-profile keyboards have hard-to-find keycaps. It also requires attention during cleaning. They are very sensitive to removal, so do not try to remove the keycaps by hand - use a 5 euro keycap puller. You will remember me - if something happens to the keycaps, you will have to contact Logitech for replacements (to be fair, they have good support).
- They have amazing sound. They have Kaihl Choc switches underneath (slightly modified for Logitech), and it is the sweetest sound I have heard from a keyboard. I dare say the sound is good for the office, it is not clicky, and it will not bother anyone unless someone pays attention to how your keyboard sounds.
- It has onboard memory. I cannot understand why this feature is not standard in other keyboards. This means that the keyboard can store the settings in its memory and does not require the Logitech software to always run on the OS. Also, this means that the lighting and settings will be used in Linux without the need for the software to run.
- Excellent battery life. With the backlight off, it lasts for months before needing a charge.
- It has micro-USB for charging. I cannot understand why they did this, but it is a downside that I have to mention. It should have had USB-C.

It is one of the most expensive in its category, BUT:

I have not seen another keyboard with these features. Its connectivity is incredible, it has the fastest Bluetooth among all competitors, and it is low profile! These keyboards cost much more than regular ones, but they are much better for the wrist and much more comfortable. Essentially, it is cheap for what it offers. There is no competition that offers all these features, regardless of price (the only thing that can compete is the Hexgears Venture, but someone has to order it from the US, it does not have such connectivity, and support is a risk).

If you have the money and like low-profile keyboards, get it. It is perhaps the last keyboard you will need to buy.

I have been the owner of a Blackwidow Ultimate (Green - Clicky) for years. At first, it suited me quite well, and since it was my first mechanical keyboard, I loved the sound.

Unfortunately, over time, the "clicky clicky" and the height of the keys started to tire me out. Even with a wrist pad, my wrists easily got tired, as did the palms of my hands, especially when coding.

So, I decided to make three major changes.
1. Switch to low-profile keycaps (which I already liked a lot on my laptop).
2. Switch to non-clicky switches (to calm my head down a bit).
3. Switch to a TKL keyboard (more space - keyboard in the center).

This particular keyboard, although quite expensive, fully satisfied me in all three categories. The keycaps are low-profile and incredibly comfortable to type on, while still retaining the feeling of a mechanical keyboard, regardless of the reduced height. I can confidently say that I noticed I can type much faster compared to any other keyboard I have tried.

I was completely satisfied with the switches. I chose "Tactile" because I wanted to have feedback when pressing a key, but not the clicky sound. It's true that they have a strange feeling, as some say, like there's sand in the keyboard, but I personally liked it and have grown to love it for the sensation it provides. I didn't particularly like the linear switches I tried, and I noticed that I made more mistakes due to the lack of feedback when pressing (except when bottoming out).

The TKL form factor suited me very well, as the keyboard is now right in front of me, without the mouse reaching the other right edge of the desk. The truth is, at first, I often caught myself unconsciously pressing a non-existent right "Enter" key or trying to type numbers on a non-existent numpad. The power of habit... But I got used to TKL within a few days, especially since we don't deal with numbers to a great extent anyway.

Finally, the build quality of the keyboard is *excellent* and gives you a tremendous premium feeling. Its connectivity is flawless, with no delay using lightspeed. It works perfectly for typing, coding, and gaming. I literally felt like I was using a regular wired keyboard with zero delay.

The only negative thing I could find is the choice of "Micro-USB" instead of type-C. It may have been done for cost-saving purposes... but whatever, it's a minor issue.

I should also mention that if you want, you can use the keyboard "wired" by keeping the charging cable connected. It still functions wirelessly with lightspeed, but the battery never runs out.

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** TLDR: A quite expensive but exceptional keyboard that I have come to love, with a wonderful and simultaneously premium feel, comfortable and with zero delay. Definitely the best keyboard I've ever had. I'm writing this review from this keyboard, and my hands are happy and satisfied.

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** UPDATE (05/12/2022) -- Almost a year later, still excellent just like when I bought it, no wear, no issues. Everything is perfect.

Hope that helps :)

Perhaps the only noteworthy wireless mechanical keyboard on the market right now. Very good build quality and I haven't noticed any delay whether I use it for gaming or just for office applications. The only downside I would say is the keycaps. They don't light up, for example, and the two indicators that a key can have, like the number 5 which also has the symbol %, are not illuminated. Maybe some people won't be bothered by this, but sometimes at night I have to double-check if I actually pressed the right button. Of course, someone can change them. With 8 or more hours of daily use, it needs to be charged once a week since you can set it to go into suspend mode after a certain period of time, so it can last even longer if you lower the lighting, etc. It's the best option for someone who wants a clean setup on their desk without cables. If it was a bit cheaper (180-200€), I believe it would be value for money. I hope it withstands the test of time, unlike another mechanical keyboard from a different well-known company.