This card is far more powerful than it may appear. Coins are spells and 1 extra mana. Certain combos require 11 mana and special setups or mana discounts to work. This bypasses that requirement.
As someone mentioned, you can get double Shudderwock without going second and getting the coin. This is quite good for that and also enables combos that were nerfed because of mana cost increases or other nerfs.
Enable Quest mage for those that like to play that one. Makes Quest Druid not get too far behind with minions and helps complete quest while 'playing on curve'. Rogue Quest gets more free mana and spells for all those combo cards and OTK potential.
Basically, gives some tempo back to those Quest decks so that the playing it on turn 1 gives something back to you later.