OK, just checking in to post first timer comments on the mod.
Background: played just about every sub (and flight) sim since GATO on the Apple ][ WAY back when.
Playing 1.5, TMO 2.2 and this mod. That's it in terms of mods.
First, as others have said, very nice improvement in the mission objectives and overall feeling of reality in terms of missions, messages, etc.
Starting in Pearl Dec 7, 1941, first mission in Luzon Straits. Only found a couple of merchants, took more torpedoes than it should have due to duds, but sunk them both (one, at night, I slowed down with the one torp that hit and damaged it, then finished it off with deck guns.)
For those who complain that there aren't enough airplanes, I don't know where you get that. Any time I come close to a Japanese port or land base that has aircraft I get a plane coming at me. Most I can crash dive and avoid damage (although my first campaign actually ended with a plane hitting us while still trying to repair some damage from a previous air attack, and we couldn't stop the flooding in time, and we sank.) From a lot of reading, it feels about "right" - if I go somewhere in daytime where I would expect some air activity, I typically see it. If I can get down quickly enough, we can usually avoid damage, but it isn't always easy to get down in time.
As far as the shipping: Again it feels "right." Read the history of the US Submarine service, it is a big ocean, and the odds of finding a few ships is low at any given time. You can easily miss seeing any traffic, find one or two merchants, or run into a huge convoy, and everything in between. If you are looking for a more arcade game, this isn't it. If you are looking for a sim in which you are guaranteed action every patrol, this isn't it. If you are looking for an experience closer to what an actual submarine commander might face at the time ---- this is it.
Very nice job, does what it does and what it advertises to do extremely well. Kudos.