Hello!
I just finished second game with Intrigue Expansion (Huge map/Gifted, first Terran, second Slyne). I enjoyed it, but I found some mistakes on a game design level. This is my little feedback for developers. I hope they wont be mad, because I love GalCiv with all my heart, and I want it to be a perfect strategy. 
1. Food and Farms
I understand this change- overpopulation affects Happiness, and this affects Government Elections. So this is another obstacle on your way to galactic domination. Now we need to search for a planets with farm areas.
However implementation is faulty, and feels like it was done hasty.
You see Carbon Life Forms need to seek planets with farm areas, and they are really occasional (for example last game I had 32 planets and 14 food total). So we will build cities only on our most important planets. Understandable.
But this does not apply to Silicon Life Forms- for them cities cost only 10 Promethion... This is most popular resource in the game, and this price is lower than recalling engineer! This is huge advantage, that will bust happiness and economy of every glass eater.
Possible sollutions:
- Increasing probability of occuring farm areas;
- Changing Food mechanics, from distributed to a gatherable and renewable reasource;
- Increasing cost of cities for Silicon Races- 10 is really low compare to 3 food (you can check it by calculating probability of appearing farm areas, and promethion planets);
2. Elections
Bonuses arrangement, and limits of planets are great in government types, but Elections... it's such a bummer. Elections are a great idea, now I need to care about happiness of my citizens, or I will get penalties.
But I can choose not to have Elections (!!!) just by picking another govenment type... Without any costs, problems, or repercussions (protests? Maybe little rebelion?). Just wait 20 something turns and change it like a pair of socks. Basically whole Election mechanic is a trouble without good reward. Goventment types are vastly balanced, so I can just choose govenment without Elections, but with other great bonuses. Without clear and substantial reward player will choose simplest, and most efficient game mechanism.
Possible sollutions:
- Increasing bonuses for govenments that Holds Elections, because lack of Elections are a bonus in itself;
- Decreasing some bonus features in govenrments without Elections, because lack of Elections are a bonus in itself;
Idea: Cabinet contains few characters, that give nice game bonus. What if in every election you will have few (2-4) new characters to choose to your Cabinet, so you can replace your current Minister with someone better.
And best part is when you will loose Elections, winning party will replace your Minister with someone who "doesn't cooperate with you very well"- smaller bonuses, or even penalties. So basically if you loose a lot of Elections you will have Cabinet that will be against you ("voice of the people").
3. Commonwealths
I really enjoy this idea, last game I even helped my Commonwealth with war, so it would grow big ( https://i.imgur.com/OsE8h5e.jpg ).
Unfortunately this mechanism is too simple and lacks features.
This is the same problem, as it is for example in "Total War Shogun 2"- you are creating vassal, but this is just another enemy AI, that starts allied with you, but can easly betray you in near future. So why bother? Just rush for technology with your favourite government, so you wont have penalty for too many colonies, or endure penalty (it's quite acceptable when you are having few planets more than limit allows).
We need something more, because this is not just another empire, but autonomous part of our empire. Sovereignty of Commonwealth should be limited, so my Commonwealth won't be able to be in alliance with empire I'm on war with (I had this in my last game)- and I have diplomatic penalty for that. This is a consequence of making tham just another empire. Commonwealth shouldn't even have option for alliances with other empires (just non-agressive pacts).
Possible sollution:
it would be really great to have some additional options in Diplomatic screen with some orders, like "you will join my war with <enemy empire name>", or "give me tribute <some amount of credits>". Every order would cost us diplomatic relations, so when we will be "bad big brother" our relations will be low and Commonwealth will rebel/betray us (but with some repercussions, like "civil war/rebelion"- penalties to happiness, populations etc.).
This would feel like real part of our federation with autonomy, and not just like another AI.
In my dream world we would have option with "war planning", like we would order our Commonwealth to attack this planet, so AI would prioritize invasion on that planet or planetary system, then we would decide if planet will be ours (big penalty for diplomacy), or our Commonwealth.
But I know this would be hard to encode.
Okey it's two in the morning here, and I need to wake up in the morning... So to be continued.
P.S. Sorry if I wrote this in wrong section, but I'm new to this portal.
P.S.2 And sorry for any mistakes, it's late, and english is my third language... So I'm not very efficient with writing.