Although I wouldn't call him a virtuoso pianist, Freddie's skill on piano was great and he was classically trained.
Listen to the "Millionaire Waltz"
There are many great artists who respect him, like Roger Daltrey.
"When we lost Freddie, we not only lost a great personality, a man with a great sense of humor, a true showman, but we lost probably the best, the really, the best virtuoso rock 'n' roll singer of all time. He could sing anything in any style. He could change his style from line to line and, God, that's an art. And he was brilliant at it. "
-- Roger Daltrey