To use it, you hold a poopy diaper over the toilet and spray it. The poop falls into the toilet, and you flush it. The wet diaper goes into the laundry basket or diaper pail (or, if you are like us, right into the wash-- we have so few of them because we do EC-- and we always have enough laundry to make a full load... then they don't need to sit around).
Its package calls it a "multi-use sprayer," so I suppose you could use it as a bidet, to help clean the toilet, or whatever else. We like it because our utility sink is outside (in our old house it was inside). With it, we can make the toilet into a utility sink of sorts; for example, washing dirty shoes or dirty feet inside instead of outside.
For its primary function, I have now used it a handful of times and it has made those poopy diapers NOT GROSS! I didn't touch poop, or get poop on anything else. Everyone says that with cloth, you just "shake the solids" into the toilet and I know that has never worked for me (they haven't been "shake-able"). If we weren't doing EC, this would be a mandatory cloth diapering item. It really makes them so manageable.