I dont claim to be an expert on anything, but i do have a degree in chemistry and can tell you that the "heat" transfer and dissipation of tradiotional air cooling at the same size will 100% be far greater. FAR GREATER. In fact, you can demonstrate that a Cooler master Hyper 212 Evo can dissipate more heat than a 120mm rad closed loop cooler.
However, you guys have mentioned being able to transport heat and dissipate it over a larger surface area. You are correct, that is one of the major benefits.
The other benefit that is often over looked is the difference in delta T between passive and active heat transfer. For instance, a standard Intel i5 CPU uses ~80W under standard operation, and has a max TDP or 91W. Both this advertised cooler, and a similar air cooled design are more than capable of handling this HEAT. however, because you are limited to the rate of heat dissipation of the materials between the base and the heat sink, an air cooler will have a greater temperature. Heat and temperature are not interchangeable terms, they mean very different things depending on the system in place. Water compared to copper is a terrible conductor of heat, but because you are actively pumping the waste heat away, the Delta T will decrease.
What will happen is you will hook this up, open Speccy and see a lower T, and think "wow this worked". But if you were to start pushing higher voltages and clocks, you will be limited in total heat dissipation. even theoretical calculations will tell you that a cooler this size filled with water will have a lower total thermal dissipation than a similar sized air cooler.
Thats just the science though...