The gigantic (yet good looking) Arctic Freezer 50 that I had installed in my ROG STRIX build always worked well. After 3 years of full-time gaming on a 51% overclocked 11900KF, the paste dried out, and I figured it was time to finally try an AIO in the build. I did my research, and since I already have a PC with the Arctic Liquid Freezer III pro, I wanted to try the new Glacier (gotta test the hype) and compare them. So far, their performance is somewhat comparable, though I'm using the fans from the Arctic Freezer on it, which are better fans in all regards. The pump shroud on the Phanteks looks better IMO, though the radiator is thinner. In all tests so far, the performance of this unit is within throwing distance of the Arctic Freezer III Pro.
The two marks against it would be the proprietary connectors, and... the placement of the refilling port on the rad forced me to modify the mounting bracket on my case.
Summary: It's almost as good as the Arctic Freezer III Pro. 4.5/10