The most important thing for me is the fact it has a little chrono in the nav map so I no longer need to jump to f3 just to check time between plots.
It adds extra commands to the officer icons i.e. raise attack periscope or obser peri.
It Also add crash dive, level off, blow ballast etc etc.
But the Chrono oh that lovely Chrono
It would be fantastic to include it in RUB as it rocks. One of my favorite mods now is this.