I won't write about whether it is convenient, quiet, tiring, etc. These are subjective and depend on what you had before. I bought it for the multi-device capability. It does what it promises there. The 3 keyboards became one on the desk. My setup:

1) Desktop (without BT) with dual boot Win7/Linux
2) Laptop with Windows 10 with Bluetooth 4 adapter
3) Laptop with Windows 10 and Bluetooth 3 (quite old but a Vaio beast)

1) Got the USB dongle for two reasons: Firstly, because it didn't have BT, and secondly, and most importantly (as I could have used a USB BT), for the dual-boot. With its USB dongle, it works even without an operating system, which means it works on Windows/Grub bootloader (as well as on BIOS). With Bluetooth connection, it needs an operating system to be booted, otherwise, IT DOES NOT work. My other 2 devices have built-in keyboards, so in an emergency, I lift the lid :)
No drivers were needed on Windows 7, and after pairing, I booted Linux and it worked immediately.

2) Connected via BT. Add new BT device and done.

3) Couldn't work on it because the K375 requires "Bluetooth Smart Ready," meaning BT 4 and above. I solved my problem by buying an extra USB BT (the TP-LINK UB500 v1 USB Bluetooth 5). So, if you intend to use it on an old machine, check what your device manager says (Bluetooth adapter > properties > advanced > Firmware version). Somewhere it says LMP and a number. You must have at least 6 or higher.

I would give it 5 stars if the light stayed on to know which device you are connected to at any given time.

Also, when will they finally get rid of the caps lock on keyboards? It only takes up space and causes accidents, a useless key...

I bought this keyboard mainly for the Bluetooth and it replaced the Logitech MK270. Due to the quarantine, I can use the keyboard for work/leisure for about 8-10 hours daily. With the MK270, I had no issues with my wrists. However, with this one, after just one week, both of my wrists are bothering me and I am considering going back to the MK270. Perhaps it's because it is quite low and so are the keys, and it definitely needs the "feet" to prevent the wrists from getting strained.

Another negative aspect is that for its price, personally, I find it quite "plastic".

It is also relatively noisy, which I did not expect, as the keys are "low".

Additionally, the keys are relatively close to each other and have a "strange" design, resulting in easily pressing adjacent keys.

A characteristic example is the "Enter" key, which is smaller than it should be...

For the above reason, it is not suitable for fast typing...

The only positive aspect is that it connects quite quickly both via Bluetooth and with the Logitech USB Unifying program.

Considering all of the above, I consider its price excessive for what it (doesn't) offer.

In conclusion, I would not recommend it for everyday use, regardless of the cost, mainly due to the strain it causes on the wrists, which is intense and evident from the very first use.

Very good feeling on the keys and the key travel is suitable for me. I use it with both a desktop and a laptop, using 2 unifying receivers, and the switching works perfectly. It has all the necessary keys and there is a setting to lock the function keys, which is very convenient for me because I use the F1-12 keys a lot on my work laptop, while on my mobile phone (which I have as a third device with Bluetooth) I don't need them, so I use play, pause, home instead. The only negative aspect that might discourage most people is that it is very difficult to get used to because the keys are flat and without space between them, so it is easy to press the wrong key. I still haven't fully adapted to it and it annoys me sometimes. I found it on Black Friday for 25€, so it is definitely worth it at that price. I use the stand for my mobile phone and it is very convenient in the end. It is high-quality and sturdy, and the notch allows you to perform gestures from the bottom of the screen without any problem, even on a mobile phone without bezels

I used the keyboard very little, so I don't have an opinion on features such as build quality, typing speed, etc.

I rated it low because the experience with Android is not good.

Although it connects easily via Bluetooth and the multidevice feature is OK, there are some issues:

1. With Android devices, and obviously this is an Android problem, which I didn't know before buying the keyboard, you can only have one active language when you have a physical keyboard connected (or at least this specific one).
So, you either have to set it to type in English or Greek, without the ability to switch languages while typing, thus no multilingual capability.

2. Even more importantly for me, when typing in Greek, it does not support polytonic, so writing a formal email or editing a document, etc., is not possible. Personally, when I write in Greek, I always use accents, even in informal communication with friends, etc.

On the contrary, when connected to an iOS device, it worked flawlessly and did everything as it should, supporting language switching and, of course, the polytonic system.