If you really want to limit its usefulness, you can give it a particularly nasty quirk in that frequent use of it can cause permanent brain damage. You have to limit it to about the rate that a human normally learns. Granted, that can still shave several years off of traditional education, but it a puts a realistic damper on things.
BTW: We're already real close to this in real-life hard tech. I don't have the reference handy right now, but somewhere some lab has had success with using computer chips to transfer the memories one rodent has of running a maze, and giving it to another... and the other one ran the maze perfectly without ever having set a paw in it before hand. It's looking really hopeful as a solution to Alzheimer patients.
BTW: We're already real close to this in real-life hard tech. I don't have the reference handy right now, but somewhere some lab has had success with using computer chips to transfer the memories one rodent has of running a maze, and giving it to another... and the other one ran the maze perfectly without ever having set a paw in it before hand. It's looking really hopeful as a solution to Alzheimer patients.