I had used it about for a while about 4 months ago, eventually abandoning it because, while it was very valuable in a tiny percentage of games, most of the time it was unused and much of the remaining time of little value when used. Perhaps jungle faction has changed that with the introduction of some interesting new auras.
The basic problem with essence exchange is that it requires either an aura you want to steal or an aura with which you want to "gift" an opponent. Excluding forest (and now jungle), there were very few auras worth stealing (safe hole, accursed, air pressure, maybe rage). And very few players seem to use forest.
You can't really even consider combos that depend upon rarely played cards of an opponent.
Thus, to insure a use for essence exchange within my control, I need to have cards I want to give my opponent. Occasionally rage might cause more harm than benefit, but all other cards with mixed blessings work just as well from my side of the board.
Unless I see some new patterns emerge with jungle auras, I do not anticipate wanting this card.