I actually don't think this card is that powerful. At least, I definitely wouldn't take it. This card, though it obviously has a lot of versatility, lacks the power that other discard cards have that make them so deadly. Cleansing replaces the cards with ones that are totally useless. Elementalist lowers bricks and quarry depending on how many cards are removed. With this card, you have a very good chance of being "out of the cauldron and into the fire", if the cards that your opponent gets to replace the old ones are just as good or better than the ones you discarded.
When choosing a discarder, if I didn't have a specific deck-type in mind to counter (i.e. unliving, undead), I would sooner take mediator or lich, or even tribute.