I use it to create as close to natural conditions as possible. Zeovit highly recommends that you strive for NSW values. I feel this kind of forces testing, basic husbandry, and observance of your tank and inhabitants. The idea is to run nutrient poor condtions while having the ability to replace or to renourish what is taken out through zeolites and skimming. The ability to feed heavily and have larger fish populations is why I choose the method. You can interpret the system and customize to your liking, as Mark mentions, he prefers the richer colors, where some prefer more of a pastel appearance. Either way, I overall am happy with the system. The only issues I have had have to do with my own ignorance to the system and investment of research before taking the plunge. I used live sand, and had many cyano issues. I also used old rock with a large amount of bubble algae to begin. I think if you start off your tank according to their recommendations, you have a larger chance for success.
GL