Overpriced and low-impact. It costs $4 and rarely causes more than $3 of damage. This is weak efficiency, you're paying a considerable amount of $ for something which doesn't hit much harder than Pop-Up Window and has much less long-term utility than $4 Kakugos or Border Controls. The kind interpretation of Karuna is that it's a slightly-upgraded version of Envelope, itself a $4 ice which usually causes a $2-swing (a fake Pop-Up Window).
Jinteki doesn't have a lot of cards I'd want to protect early with a Karuna, and those cards (Rashida and Regolith Mining License) usually work better early with low-cost end-the-runs like Whitespace or Vanilla. Karuna costs enough that you probably wouldn't want to rez this early on a central server unless you have some econ running by that point. Spoiler: as Jinteki you probably won't, your economy is usually the slowest and the least able to bounce back quickly from a $4 expenditure. Even Kakugo is hard to pay for sometimes and it is a Jinteki workhorse which produces considerable long-term value for a short-term tempo loss. For an extra $1, you can get a Saisentan which is devastating enough on early facechecks that you can feel fine even if it bankrupts you.