In terms of value added it does nothing for us. Seems like a clunky poorly thought out mechanic that was added just because someone at blizzard said, "add one".
It is the only mechanic in the game that limits a classes choice of spell usage. So it really feels like it takes away from the freedom to act. PVP especially.
I just came back to Balance recently having gone away from it in classic when the chicken came. I refused to play a chicken.