I'd give it a 5. The colors are to uniform, the rockwork to catered, and the shapes of coral to consistent. I would recommend you look at getting some Hagen HO T5 retrofit kits, and up the lighting for a couple hundred, to open up your options.
Well, we are going to scrap this exhibit soon. I got approval to open a new floor to ceiling tank designed for a reef instead of putting a reef in a basic tank.
Make the rock piles asymetrical and more diverse corals. Multiples, no matter how nice the specimens, are not as good as a single higher grade specimen. The best reefs I've seen take your breath away and never leave you saying there were more than one of anything.