You know, I completely disregarded the whole no bonus for duplicates. It probably is fine revealing 3 cards.
I think it might be good enough to buy semi-often if it revealed 2 and gave a bonus for duplicate cards. In the early game, that version is most likely to hit Estates and Coppers, which would produce non-terminal $2, Peddler, or Lab. Now that I've typed that out, maybe it is too weak for $5. Seems probably a bit strong for $4 though... perhaps not.