Generally I'm a really big fan of this game, so I don't want to make this sound like angry complaining (I'm not angry, I'm a satisfied customer), but I think the naval aspects of the game can be improved in at least two areas.
Scenario Start Balance:
Historically, when WW I launched, there was a vast disparity in the fleet sizes of hte major powers.
Austo-Hungarian Empire: 4
In the game though, all five of these powers start with a *single* 10 strength battleship counter.
If you want to assume that a counter represents a 4 ship squadron, then you'd want to start:
UK ... 7
Germany ... 4
France ... 2 or 3
Russian ... 1
Austria ... 1
Starting everybody off at one counter each means things like Russia can contest control of the baltic, or that the austrians can decide to challenge British naval supremacy because, hey, they basically start out tied.
Maybe its just me, but even mid war submarines seem to have limited ability to attack even convoy escorts on the high seas. When a full strength 10 point submarine counter consistently trades 3 damage to a convoy for 2 damage to itself, the whole value of the submarine is questionable.
Likewise, the use of submarines against dreadnaughts isn't well modelled. During WW I, submarines actually accounted for quite a few dreadnaught and pre-dreadnaught kills (I pretty quickly got up to 9 capital ships sunk by submarines), which is actually more than the combined butcher's bill at dogger bank and jutland.