I have it. I don't think it's any harder to keep clean than white sand. I vacuum it every 3-6 months but have massive flow in the tank that probably helps keep it cleaner than some. (I would have an all out sandstorm if I had something like oolite.) I think it completely changes coral and fish selections from what most people do with white sand tanks. I would never put an Achilles or Black Tang in my tank. Not because they aren't striking fish but they don't contrast well against my black substrate. A plain old Yellow Tang or Coris Wrasse on the other hand is striking! My Orange Frog Spawn looks incredible with it. Dark/deep colored acans. Not so much...
I also have a TON of light going into my tank. I don't have to rely on a white substrate to reflect the light to make it look brighter. When some people go to black they have a hard time adjusting to the tank looking darker or dimmer due to the substrate absorbing light. If I put in white sand you'd have to wear sunglasses to look at it.
I think it's something you have to plan from the start and choose your fish and corals based on it. I look at my substrate like a hardwood floor and how it influences decorating a room. Wall treatments, couch colors, rugs, etc determine wall paint colors or vise versa.
If you started with Black and got several corals and fish with it in mind, you'd probably be happy going back. Just crank up the flow and get some undertow going to keep detritus off the bottom.
