Hi there!
Just a few quick thoughts I had while playing the game:
It would be nice if there was a "next available unit" button (or am I just missing it?), and it would be nice if you could double-click the mini-portrait of a garrisoned unit to have them leave a city, rather than that teeny arrow button on the top. Also, it would be nice if you could (as in GalCiv II) control where that unit would come out, or at least bias it towards any roads nearby.
Thanks!