The 24-year-old completed his move from Tottenham to Real Madrid in a reported world-record move on Sunday.
"Bale has an extraordinary left foot. I have no doubt that he will do well at Real Madrid," Pique told Onda Cero.
"He has really grown a lot in the past few years. He has developed as a player and has gained a lot of experience.
"He has joined a big team that paid a lot of money for him. Time will tell whether he's worth his transfer fee."