I am a fan of simple clear gui, current gui suits me well, the only two extra things i would add:
1.Fire icon diuring battle screen - sometimes you need to take off headphones - diuring boarding i always think im on fire...
2.Markings for whole 32 rhumbs on compas rose - it would simplyfy fleet operations on open world. The same "on click" rhumb grid/rose i would add to game map. Idea how it should work you can grab on tdamap http://tdamap.com/portmap.html .
Another thing is customisation, i belive that setting size of elements and position by user is a must.