I'd say the previous reviewer didn't quite get this game. Obviously this game is slow without time compression on, as it simulates real-time submarine warfare. There's a lot of sea, not many boats, and submarines are slow... Time compression is unsurprisingly provided up to 1024x...
The crew don't seem to get tired at full acceleration to avoid you having to overly micromanage, but you will find crew getting tired during long engagements. Best avoid long engagements...
Depending on the mode, the sonar operator's detected contact lines will appear on the main map. Torpedo aiming is a difficult art, and requires careful management of the sub's direction and some gut feeling as to what manoeuver a ship is likely to attempt. Don't expect them to behave like photon torpedoes (although the later wake-homing torpedoes are fabulous against warships).
It's an odd game, and I think it's somewhat heavy on realism and low on fun, but it's still a sound game. If only it didn't use starforce copy protection.