If you have played the "Uncharted Waters" by Koei back in the 90s or any other game that was derived from Sid Meier's "Pirates!", where you travel from port to port with your fleet, do trades, fight pirates, fight those who aren't pirates, attempt diplomacy with big nations, Starsector is pretty much that in space.
I think it's probably safe to say that if you are familiar with such games and the genre, and have liked them before, you'll like this too.
It's got almost everything a game in this genre usually has, and maybe a little bit extra and a few things new, but does not seem to hugely break the mould.
However, it does appear to do the same things a bit better. Starsector has lots of ships, lots of ways to customize those ships, various dialogues and flavour texts, myriads of missions, a more complex port economy system, a big map, and etc.
Simply put, the universe does not feel stagnant and the AIs feel like they indeed do have some intelligence.
While this game is supposed to still be in development, I haven't hit any obvious bugs or issues, and the game feels as good as a finished product. It is a good game and a good purchase.