No units level up, no espionage, and AI does not expand properly (Conquered a few planets only).
Level ups will be with commanders expected to be part of a later expansion package.
Espionage is also expected to be part of an expansion, after all it was an expansion in Galactic Civilizations II: Twilight of Arnor.
AI will always be a work in progress, this also depends on difficulty level you are playing at as well as if this was a custom race what are the growth and expansion traits.
With respect to diplomacy, dialogues often do not correspond to the diplomatic situation with a faction.
I agree this could use some work. 
I miss the "land" battles of stardrive 2 .... and heroes.
There will be an invasion battle viewer similar to the combat viewer currently (most likely not as involved) is said to be updated in a future free patch.
