I have it for 2 years now.
The processor is a refrigerator, so that goes in the pros.
What everyone says about the size of the refrigerator is wrong because all implementations have almost the same size.
In the cons, I put the noise which I think has increased.
In the neutrals, I mention the fact that its RGB does not synchronize with Asus boards.

Very nice cooling, and efficient!
I have it on a Ryzen 7 2700x processor for gaming and it doesn't go above 38-40 degrees!!

In general, it's good. You can't exactly call it quiet, it depends on the CPU overclock and load. It's not ideal for extreme overclocking, it's for around 170 watt TDP. After that, you go for a 360 mm and above. I have the i7 7800x, which is at a similar level to the i7 8700k in terms of temperatures, and I managed to take it up to 4.7 GHz with 1.25 Vcore. Now, in Cinebench, which is one of the hottest benchmarks out there, I'm at around 85 degrees Celsius. If I run it continuously, it goes over 90 degrees Celsius. The installation, although easy, is not ideal in terms of cable management. It has many cables coming out of the pump and it's not convenient. Overall, I'm satisfied though. The price is a bit high, it should cost at most 120 euros.

I use the aforementioned liquid cooling to cool an i7 8700k.

It does an incredible job and is very quiet. I replaced the fans it came with and installed Corsair ML 140 Pro. The cooler is a bit bulky, but if you have a serious case, it fits easily. It fit very comfortably in my Fractal Define R6.

Very good liquid cooling and always with Corsair warranty!

I use the Corsair hydro cooling on an i7 8700K and I am extremely satisfied with the temperatures. The fans are 140mm and completely silent, but the whole system is bulky and requires a full tower to be properly installed. There is a regular USB cable for the pump to communicate with the motherboard, which could be placed more aesthetically. Cable management was challenging for me. Other than that, it has a five-year warranty from Corsair. What else could you ask for?

Well done to Corsair, many improvements... it is now better than NZXT with 140mm fans instead of the 120mm ones stated here