Enjoyable and fun game experience. Can be a little frustrating at the beginning but once you get into it will consume you. Lore of the game is really interesting , races are well designed and unique. AI isn't that great, even if its you best friend he will probably attack you becouse 1) you have a higher score than him 2) he has no room to expand. So yeah diplomatic is kinda hard in this game, one of the most difficult victories to achieve.
There is also a supremacy ( aka conquest homeworlds ) , expansion ( own 3/4 of galaxy ) and wonder victory.
So I suggest cooping with a friend becouse its always more fun. Games lenght depends on your map settings, they can last few hours or even days. There is lots of customization when it comes to the galaxy settings, like shape , size , ammount of planets and their size, events etc.
Races are also great. There is a race that devours worlds so they need to expand if they want keep their strenghts up, pacifist robots , religious robots , various humans sub-factions, et's , some kind of samurai aliens and finally my fav race Harmony.
Race made of living crystal that wants to purge galaxy of dust ( aka gold, game income ).
There is also an option to modify current races and select different traits for them, its a fully customizable.
Soundtrack is amazing, really enjoyable to listen.
~~What are the minuses ?
AI cheats a little , how is that possible that he can manage so many fleets and still have a decent income.
Combat system is unbalanced. Kinetics op - even when they were designed for close combat they deal sick dmg at LONG range, just go full kinetics and every game is won.
Bomber units are useless.
UI could be a bit better. Becouse later in the game micromanaging your entire galaxy gets a bit annoying, yes there is an AI governor to help with that but that isn't always a good option to choose.
And many other small things that you will probably get annoyed by them and you will think "what the heck devs where thinking".
So yeah , its worth a money especialy when its on the sale. Buy it together with the Disharmony DLC becouse it adds lots of new stuff and overall gives a better player experience than vanilla.