The NH14 is only a pound more than this thing and Noctua recommends using it in test benches and removing it when your PC is in transport. The size difference is great but the pound difference not so much. AIO units are getting more popular for a few reasons, and the biggest one is getting that weight off the center of your board. I used to use a TRUE120 for the longest time but never wanted to. Let me reverse that question, how is having a hunk of metal hanging off the center of your motherboard good for it? Look at how video cards sag because of aftermarket heatsinks. Your motherboard is strapped down to your case but has the same amount of pressure put on them.
It is relatively tiny compared to similar sinks in that price range, like the 212 EVO. It has a low RPM 92mm fan that can't be replaced with conventional fans to increase cooling performance. The EVO has a 120mm fan that you can put a Noctua fan on it for maximum silent performance, or something ridiculous like a Scythe Gentle Typhoon. You can also do push pull with it for even better cooling performance.