It is definitely excellent and I did get a playset so I have the option, but usually against control I am bringing in Duskmantle Seer and an additional 4 drop is the last thing I want. Although whether I should use the seer is an entirely different question.

I used to side seer in against Pillowfort, Midrange and Reanimator. Probably not great to use against your standard esper or american control decks. Although revealing a Blasphemous Act can be hazardous to their health.

Or an AEtherling , usually I have poked through quite a bit before I drop the seer, and as long as I save the counters for the revelation they aren't gaining life.

I might take out the Dryad Militant for Notion Thief now that I have access to the Ooze