ghost shrimp are great! They really made a difference in keeping my tanks cleaner. I lost all of them in a recent salt treatment for ich, and the amount of waste on the bottom (mostly broken up food) is so much more. They're not hard to care for, as long as your tank is cycled and mature.
Besides that, they're tons of fun to watch! I had two shrimps, father and daughter, who would both turn upside-down at the surface to catch flakes. They didn't learn this from each other, as he died right after she settled from the larval planktonic stage to the baby shrimp stage. So maybe it was genetic? Neat, whatever it was.