Kind of fun in that they interact with each other. I would add a Setup rule similar to Young Witch -- if any one of these three is in the Kingdom, add the other two as well.
I think it would be more interesting if the card effects themselves countered each other, rather than just adding in a Reaction that negates something else. The other thing is, although you have the defenses in place (Scissors doesn't effect Rock), you don't have it going the other way around (Rock is superior to Paper).
On the specific effects themselves...
Rock: Very similar to Cutpurse. Despite costing less, it's almost strictly superior in that opponents must discard a treasure card, not just Copper. "Discard a treasure" remains a decent attack even into the late game, whereas Cutpurse falls off.
The fact that Cutpurse grants an extra $1 means that Rock is not strictly superior, but I think it's still stronger overall.
Scissors: Very similar to Oracle. Aside from the Reaction, the main difference is that Oracle lets you adjust your own deck and Scissors gives you the power to rearrange the cards, not your opponent. So, not strictly superior again, and I wouldn't say it's stronger overall either -- it would depend on whether there are Kingdom cards that effect the top cards of opponents' decks, like Swindler or Tribute.
Paper: This is way more fun as an attack... Estates would run out so quickly.