Keep them coming, I'm loving it so far because you're no longer shooting fish in a barrel, the fish can now shoot back! In addition to the possible inclusion of a fire suppression system and bilge pump system to pump out flood water whilst submerged, would it be possible to pull into a friendly port and have torpedoes replaced and existing damage (especially to the outer hull) repaired, so you are once again good to go? This would make for an interesting limp back to a friendly base after sustaining heavy damage, whilst avoiding detection by enemy vessels and aricraft. Also, sonar/hydrophone functionality is essential for shipping detection, albeit limited, when completely submerged.
This could be useful for sound effects
http://www.subsim.com/radioroom/showthread.php?t=206077
edit: re the fire suppression system, i reckon it really would need to prevent a fire for 30 mins - 1hr, as I've just had a killer time with a fire in the torp room whilst submerged to 14 metres. The fire destroyed one of the fuel bins as well as breaching the pressure hull letting in water and putting the fire out. I surfaced the boat draining the water out and sent someone in to repair the fuel bin. A large fuel fire broke out, killing my repairman. I had dive to 1 metre, flooding the room and extinguishing the fire, then resurfacing to drain it again, then send in another repairman. Repeat steps with repairman, fire, death, flood, drain, repair, fire etc until I'm running out of sailors!
Oh, what to do?
I can't wait for version 0.19!!!
further edit: Given your list in post #1, here is my list of importance.
- User interface
realistic subsystem panels would increase the realism, rather than a screen of plain text
- Realistic modelling of submarine systems
we've already discussed a couple of good ideas
- Graphics
a bit less blocky and a bit more realistic is always welcome
- Realistic modelling of environment (water physics etc)
undersea currents/thermal layers could be a possibility
- Lots of missions
escort or surveillance missions would mix things up nicely
- Setting (WWII / cold war / modern)
personally I like the current modern setting
- Historical accuracy
- Lots of different playable submarines
these last 2 are 'as and when' for me.
Rock on!