The first expansion pack, Rising Tide was released two weeks ago. I haven't bought it yet cause I'm super broke atm, but they also updated the base game.
Speaking as someone who put ~30 hours into the pre-patch version, it feels like an enhanced port. Not a totally new game of course, but substantially more fleshed out. The Unit Upgrade screen has been completely overhauled, the Technology Web is signficantly more colorful and easier to understand, and the interstitial dialogs after completing most actions have full text and new illustrations. It just feels like a significantly more content-full experience.
I can't speak to any underlying balance tweaks or whatnot yet, and it won't change anyone's mind about the game, but it does feel a little nicer now. Might end up dumping another 5-10 hours at least.