I was skeptical about the look of a BB tank before I tried it almost two years ago. Yes, at first, it looked unnatural. Over time, however, the bottom got encrusted with coralline algae, so it no longer has that "bare" look.
The greatest benefit is being able to siphon out crud on a weekly basis. You absolutely wouldn't believe how much crud comes out of our 120g
We do two passes with the siphon, pictured below:
The first pass is to get all the loose stuff from the back of the tank. Then we use a turkey baster to blow the crud out from under the rock to the back of the tank, and siphon out the rest. The water in the pail is totally brown
Here's a pic of what we used to get out of our BB 67g when it was running compared to a pail of new salt water. The 67g cruddy pail looks clear compared to what comes out of our 120g:
