The full release notes are on the Arcen forums. This release is basically dozens of little tweaks and bugfixes, rather than any particularly huge new features. However, that said, some of these smaller effects will have a pretty enormous effect on advanced play (as with most small tweaks in any strategy game).
The first of these is the new buffs to the Military and Logistics command stations. Those command stations are relatively new anyway, but players were complaining that in most cases there was not enough incentive to use them. Well, we listened, and these now have substantially larger bonuses associated with them that cannot be achieved via any other mechanism at the players' disposal.
The second notable change is to transports, which have been nerfed. A lot of advanced players were using transports as a way to do flash raids against the AI by pulling the transport up to reinforced enemy targets and then "blowing the walls out" (scrapping the transport) to dump all their forces out at once. This patch puts a stop to that, evening back out the playing field, while still leaving the utility of transports intact for bypassing overpowering wormhole defenses and... for transporting.
The third notable change is to the display of the galaxy map (pictured right). The lines between planets are now colorized based on the relationships of the planets (friendly to friendly = green, friendly to neutral = yellow, friendly to enemy = orange, enemy to enemy = red). This makes it vastly easier to at-a-glance parse the visuals of what is going on in any given galaxy, and to keep track of all your planets. It's also a lot easier to quickly see when a planet is lost. The effects of Supply are also now easier to see, as they are denoted by line thickness (thicker lines mean human supply) rather than with a faint underline below the regular lines.
The fourth notable change is to how the AI uses "support ships," specifically forcefield bearers, munitions boosters, zenith autobombs, shield boosters, and neinzul youngling nanoswarms. All of these ships work best in concert with other ships, so it was always an easy wave to just ignore when these would come in as a homogeneous wave to human planets. The AI now only seeds these into existing waves, to make those waves more powerful, rather than using them as standalone waves.
Beyond that, there are a bunch of other more minor tweaks, and a lot of minor-to-notable bugfixes. Enjoy!