Having played something like 25 games with Brood war, I think that the Queen of blade is too strong in 1vs1 games due to the leadership card where you can have 2 bases-6 zerglings-2 transports and 8 workers. You have so many options with 2 bases...
I haven't seen a game where it was very close between the 2 players. Our group is seriously considering nerfing the card somewhat.
In games with more than 2 players, it seems to be balanced enough, but maybe there was some other factors involved in those games
What do you think?