This will probably be the card that kill as many runners as Snare!. This will encourage using ambush in your deck, since you want the runner to be scared of running unrezzed cards.
Of course, at 3 to rez, you need to have a good economy to use this. Especially since you'll usually need two of them on the board to flatline the runner. This card is almost an auto inclusion for Jinteki: Personal Evolution and will be part of the game plan for most Jinteki kill deck.
Even out of faction, at 2 influences, it is worthwile to use it. It pairs well with deck that use End of the Line to ensure a kill. NBN: Controlling the Message loves this, since you still tax the runner for trashing it.
A great asset to use along Reaper Function is Bladderwort. You can rez Reaper Function to go under Bladderwort threshold and thus do at least 3 damages.
With this, stealing an Obokata Protocol on the last turn, even in another identity than Jinteki: Personal Evolution, become a possible death sentence.
Incredible art and quote, for an incredible card!