I'm dealing with sand for the first time in my 150, and let me tell you. I prefer it over gravel. The obvious difference is that fish wastes settle into the gravel, giving the illusion of a cleaner tank, but come vacuum time, we find differently. With sand, fish wastes settle on top, letting you know exactly what state your tank is in. So if you like a clean tank, sand is for you. If you like the illusion of a clean tank, stay away. If you are concerned about sand loss through vacuuming, don't. I lose more gravel than sand.
Aside from the obvious, sand has disadvantages by the score. When first adding sand, it produces silt, which quickly bungs up your bio filters. When I cleaned mine after filtering out the silt, it weighed about 8 pounds. Also, sand doesn't support beneficial bacterial cultures like gravel does, which means you need ample decorations to provide some solid surface area. Also I've heard mention of anaerobic bacterium growing in deeper sands which can be harmful to fish.
One other downfall to sand, that I've found in my own experience is that it tends to stick to the slimecoat on scaleless fish, which is particularly disconcerting if you keep lazy bottom feeders like my SA red tail.