The cards are 100% NW compatible - just made appearance changes: more visible fonts for weapons, translation into Hungarian, used a few icons instead of text and made it more printer friendly. Laminated them for re-usability.
It's not only that submarines are fun to play, they started making sense when we noticed that IJN ships do not really add to the AA protection in this scenario. They are lousy AA defenders. IJN player started picking subs (which are quite deadly), so US player also had to pick destroyers to counter them. Since US subs are not that strong, maybe USN should have picked something like HMAS Australia for AA protection instead of subs. Maybe in the next game 
Funnily, this was our first game where subs did not make any direct impact on the battle outcome. In previous 1.4 version games usually Japanese subs wreaked havoc among US carriers.