A quick break down of what struck me the most in my first few plays:
1. Too much micromanagement:
I'd love to be able to designate "production worlds" and the like via a governor system. Likewise I'd like to be able to set "global" production allocations for each type of governor rather than just *everything* or 1 colony at a time; this should be able to differentiate between "improving" and "mature" colonies as well, seeing as there's typically a far great focus on planetary improvements during the growth phase.
I know the governor system isn't in yet, but please try and make it 100% automated with optional player alterations (basically what the AI uses). Continually changing each governor as new techs are unlocked is a hastle (also it'd be inefficient with the current adjacent improvement bonuses to just have a fixed list of builds).
2. Flavour text QA:
I can't remember what/where, but there were a fair few cases of spelling mistakes/incorrect usage of words in tech trees and such (e.g opposite of what they meant). Playing as the terrans I noticed that one of the terraforming options (Ultra-Terraformers?) said it would TF one tile, but actually worked on a bunch of tiles. Likewise the alterians had something that claimed to TF any number of low quality tiles, but could only build once...
3. Can only finish one build/research queue per turn:
If I make a planet with 3k production it seems silly that I can only build 1 ship per turn. Same thing with improvements- it's nice that I can build the basic factory and upgrade them, but right now that could take 50+ turns on a large planet when it COULD finish in 3. I also noticed it was impossible to end turns without having something build on a planet, so I'd have to put (e.g economic stimulus). Not huge, but it meant I might not receive an idle colony notification so I could go micromanage production values or something.
4. Credits are worthless:
Once you've covered maintenance costs there isn't much of a need for credits. The occasional buyout is nice, but that can only be done once per turn anyway.
5. Bonuses are poorly described/applied:
I'm not entirely clear on how I end up with X production, how population growth works (etc). It'd be nice to have a clear breakdown and indication of which/any bonuses multiply with others and which stack. Some bonuses certainly do need to add multiplicatively or they're useless: I built an economy starbase and noticed the + manufacturing bonus was pretty much worthless weighted against the factories on my planets.
I'm sure there's a bunch of other stuff, but hopefully this helps someone.
Edit: Changed the description of 3. to avoid confusion.