For me it would be:
- more Mission types in the campaign
- a soviet Campaign
- more different sub skins
Another thing regarding Sounds. You could ask this guy:
(
Jive Turkey) for recording a few sounds. As far as I understood he is an ex submariner and knows how to speak the correct commands and sounds just as you would expect. He is doing a lot of live streams and seems to be dedicated to the game and submarines. Just a thought.
Regards
Sebastian