One of my biggest disagreements is the "concept" that one sub counter equates to a certain number of subs. This would be fine if subs acted in battle groups. But the fact is that a sub is a solitary hunter. Even in the day of the wolf pack they acted solitarily. Giving a RN battle group the chance to wipe out a 'fleet' of them at one stroke seems silly. For them, the subs, to be effective, you have to have at least half a dozen. If going with the 'concept', you've built over 600 subs. And they still die like lemmings. I think one sub should be one counter, at a suitable price.
Next. Air units take too much damage from surface vessels, and air units are too powerful against surface vessels. One reason Seelowe was called off was because the Luftwaffe couldn't be certain that it could sink the RN heavies. Other air forces were far behind the Germans in the early years of the war in air-to-surface attacks. And there was certainly no way any surface squadron could destroy 1/5 of an attacking air fleet.
Defending air units only get one chance to impede an opponent's air forces. Imagine how the Battle of Britain would have gone if after the first attack by German bombers, the rest attacked scott free till the next fortnight.
The old phrase "It takes 3 years to build a ship" is still close to true. Raising or refurbishing ships in a fortnight is just plain wrong. After Jutland, most of the vessels that suffered serious damage on both sides were in drydock for 10 months to a year. Perhaps ship building time could be made more realistic, and units already under construction at the beginning of the war, like the Bismarck or Prince of Wales could come in at some scheduled date.
The real satisfaction in the game is it's ease of play, and the fact that it's one of the very few in which one can even try to subjugate England. Forcing that surrender is enjoyable indeed. Perahps with some tweaking it could be made more desirable for those of us over 13 years of age.