Shrimp and snails can break it down, and fresh water clams can aggitate your sand.
Personally I never cared for sand since I have a planted tank and want good O2 flow. I also never vacuum more than just the surface since the broken down debris is a good source of nutrients. Just keep the top free of built up mulm (dead plant waste mostly). The key is that it is broken down, which takes shrimps, snails, and/or other bottom feeders.
Sand is also a pain if you ever get blue-green algae. For most things you can wipe it right off and pick it up, but it binds better to sand.