Having been brought up with classics of 4X galactic conquest (The 4 Xs stand for eXplore, eXpand, eXploit, and eXterminate) like Master Of Orion, Birth Of The Federation and Imperium Galactica, I might be a bit spoiled and gotten my hopes up too much over what everyone was saying for Sins. It's a good game, there's no doubt of that, but it feels less like a strategic conquest, more like a big, strung out skirmish, with heavy emphasis on eXterminate and not the other 4 X's. The options for building up planets under your control are very limited. Basically all there is is “Upgrade Population”, which increases credit revenue “Upgrade max number of Civilian/Military Buildings” which does just that, and “Explore Planet”, the latter of which sometimes reveals artefacts which give your faction a bonus.
Diplomacy also seems to be pretty broken, and shallow. Your opponents will give you “Missions”, which are basically just cold-call demands for money/resources or killing X number of Y opponent's Z's, which, if completed will make them like you more. Blowing up their ships doesn't seem to miff them very much, nor does putting outposts/fleets too close to their borders, (like in a game such as Birth Of The Federation), and I find it disappointing that you can't actually make any demands of THEM.
Hopefully if they choose to make an expansion, or sequel for the game, they'll add in the depth they missed out on, but I won't hold my breath. Master Of Orion 2 and Birth Of The Federation have held their age well and they still run on XP so I'll keep my lust for galactic conquest sated with them for now.