Borrowed a friend's copy, spent most of last night playing it.
It definitely has its charm (SPACE BEARS) and while combat feels very GSB-eqsue (design ships then let them slug it out), it's still fun.
Ship design is pretty cool, though it takes forever to assemble the bigger ships.
The econ mechanics aren't too bad. I think the trade mechanic - you can build freighters and have them ship production, food and people around as needed (unlike MoO2, they actually exist in the game space) - is quite clever myself.
On the flip side, the UI is concentrated arglebargle. Worst offender for me is that it doesn't notify you if a planet's production queue (or your research queue) is empty; it's easy to get a lot of wasted downtime. Runner up: WHICH SELF-RESPECTING RTS DOESN'T LET YOU QUEUE ORDERS AARRRRGH.
Some elementary things aren't explained, like how to create troop shuttles or the use of subspace platforms to create "roads."
Economic management breaks down late game with a dozen and a half planets to manage. I could use the governors, but I've never trusted them in a 4x game, and I've not heard good things about the ones here.
Tech tree seems a bit cropped (though it's far better than being massively bloated like Endless Space or FreeOrion). In my current game, I've run out of topics to research about 300 "years" in.
Diplomatic interactions felt a bit off. Inevitably, the militant races would smell blood and come after me early in the game, although I could hold them off. In my current game (the only one I've made any real progress in) it eventually boiled down to an alliance of civilized races (humans, space bears and talking plants) against the marauding hordes of cthulhu monsters, woolves, mind-controlling molluscs and robo-bugs. I think the only thing that saved us was the fact that the aggressive races were just as likely to fight each other as fighting the pacifists. Eventually the wolves and cthulhu aliens succumbed to the infighting, and now I'm trying to subdue the bugs.
I'm winning most of my battles, but they seem to have an endless supply of ships, and in terms of territory it seems to be two steps forward, one step back. I'm almost within striking range of their homeworld now, though, and when I do I'm going to go Fallen Spire on their ovipositors.