The UI has a few major problems with it that I see.  Too many important details are hidden from the user or are not easy viewable.

The most glaring example is when the button becomes "Turn".  Not "Next Turn", just "Turn".  This button is small, subtle, way in the corner.  And "Turn" is the same color as any other state.  I spend half the game clicking on this one button.  Going next, next, next (not just turns but to do my next action).  Why is this button so small and innocuous?  It should at least be colored to indicate special states like Turn is over now.  Some indication to say, "Hey dummy, everything is complete and you really probably should be clicking this button now."  When I play Civ and my turn is over, I know it.  In GalCiv, I tend to miss the fact that there's nothing more for me to do until I notice "Turn" staring up at me.

Another example is the Moves remaining in a ship.  Click on a ship.  Does it have moves left?  In strategic mode, you cannot tell except by looking somewhere in a table at the bottom.  In non-strategic mode, there's a spinning circle around the ship (green/red).  Why is this not in strategic too?  In fact, why can I not see this for ALL of my ships without even clicking on them?  Isn't that kind of important info (which ships can still move)?

Third example.  Planet special qualities.  These special qualities pretty much determine what you should be doing with your planet.  They are extremely important.  If you've got a planet that gives you 50% manufacturing and -25% food... what should you build on it?  Pretty obvious, right?  Except it's not obvious 50 turns later when the only way you can now determine what the special qualities of that planet are is to mouse-over a tiny icon under Planetary Defense.  With a random name like "Shielded" etc.  This is critical info for the planet.  If it got it's own window and art, that might even be appropriate.