Positive fan responses appreciated the outfit's breathtaking regal look, old Dior atmosphere, Kate's style risks, and new, exquisite appeal.
Some thought the mismatched blues didn't work, while others thought the outfit had too many shades of navy.
The hat was also criticized, with some suggesting a white hat would have been better.
Kate's stylist was even called to be fired by one fan.
The outfit was seen as a clever decision as the designer, Erdem Moralıoğlu, was born in Montreal, which has ties to the Commonwealth.