Yes, Jonas, as in "regular cards" there's no upside down, they're perfectly mirrored (well, except for odd numbers, where the center symbol would be facing one of the ends) - even the "character cards" are split, either horizontally or diagonally, and display a mirrored image.
It's still better to keep the corner number this way, as it makes for easier reading of the card value, no matter which way up the card has been dealt to you.
