I'm pleased with the Alpha 3 update: there are some minor issues (https://forums.galciv3.com/455484 has a good list already), but in general, the new planetary interface looks good.
Compared to GalCiv 2, I already like adjacent boni (making planetary development fun again) and starports. Both features feel like "how it should be".
Feeding a starport from multiple planets sure is great fo giant ships. I'm not sure about building a fleet of tiny peckers, though: if my production is a multiple of the cost, will multiple ships be built in one turn? (Or is that maybe a bad idea?)
For me personally there are a few (minor) immersion issues with the starports:
First, since construction is now obviously in space, and resources can be distributed freeely between ground and orbit, I can't stop thinking of the cost of launching all that stuff into space. (it could be said "it's included in the production cost", yet it feels missing from lore / tech tree / assignment)
Second, the "0..100" slider between planet and ship construction feels "socially overpowered". For sure an underdeveloped planet might have an issue with diverting all resources to build colony ships. I could imagine repercussions for extreme settings (e.g. diminishing returns, or affecting happiness), or progressively unlocking settings through research.
I do hope combat gets a makeover (compared to GalCiv 2). Rocket/bullet/laser are uninspiringly symmetric, and the differences between them always felt too little to count. Maybe I didn't grok it, but it was always "look at the first enemy ship, research the respective tech lines and hope the enemy doesn't switch". The improvements also seem pretty linear, the main strategic choice is "breadth vs. depth". After all these years, that's not good enough anymore.