Read several of the posts, but to answer the OP, I'm a fan of it. It's simply amazing we can keep pieces of the ocean alive in our living rooms. Nature adapts. The particle size, composition, breakdown and use of every atom in a reef tank can be debated ad nauseum. Bottom line, we are trying to recreate a natural reef which is a very dirty place. Anyone that has ever swam through a reef has a dirty crevice or two to support this fact.
The biggest difference is the magnitude of the enclosure. In reality, the ocean is an endless supply of nutrients in and out; those currents are ensuring new water is hitting those corals 24/7. Our tanks are recirculating the same water over and over again until we do water changes and of course supplement the water.