TL:DR I like it a lot, even if it is not the hardcore space sim a lot of people want.
I'm in the same position as this - and I say that as someone who loves their background-artificial-life depth to be high, usually. The X series (before Rebirth) were hugely appealing games to me, and X3:TC still holds highest playtime on my Steam account. We'll ignore how much of that might've been due to misuse/abuse of SETA.
So I bought Rebel Galaxy and started it up with medium-level hopes, having read some of the comments here about the limited depth on offer. I figured it'd give me enough entertainment to make the £13 worth it. I just wanted to recapture a bit of that old Freelancer feeling, to be honest, and while I've got and played Starpoint Gemini 2, it never gave me that same feeling.
Rebel Galaxy does. I don't know if it's the graphics, the (yes, somewhat Firefly-like) music, or the more arcadey, less sim-like controls, but I've been having a blast both literally and figuratively. I'm about five hours in and haven't left the first system yet (I think there are fourteen). I've not felt any pressure to chase the main plot - I've been enjoying cruising around, picking up missions here and there, shooting up groups of baddies (and occasionally goodies because, hey, you're carrying stuff I want), and exploring the various nebulae and asteroid clusters that are scattered around.
I do run into groups of ships at quite regular intervals - and I'm not sure whether they're event spawned or not, because (at least on the surface) it does feel like there's quite a lot of life occurring. I know some stations are in a state of war. I know some are under siege. I know some are experiencing a famine, or an economic boom, or a crime wave. I don't think the simulation is deep enough to link these explicitly through cause and effect (they're random events, I believe), but at a player level I haven't felt that mattering to me. I stumble across a big fleet of bad guy capital ships warping their way through space and it
feels right, because I know there's a warzone not far away. I find a trade convoy with a fighter escort and again it
feels right, because they're the famine relief that set off not long ago. I pick up a distress call and I know it's either a trap or someone in deep trouble - and either way, it doesn't matter to me whether that's as a result of a deeply simulated sequence of events or it's just the roll of a die...because it doesn't matter. They're both in-character for the world and they're both fun. And often !!FUN!!.
As I say, this is coming from someone who used to love watching the trade convoys depart from stations in X3 and seeing them having an effect upon their arrival, seeing how embedded they are in the world. Rebel Galaxy doesn't have that same degree of simulated life, it's true, but it has the right abstraction of it. The game doesn't feel cold, grey, and dead...which is, sadly, how Starpoint Gemini 2 felt (to me). It feels like Freelancer did - colourful, alive and dangerous.
The camera bugs me a bit when I'm aiming my broadsides, but once I learnt to check my heading
before lining up my shots it became a lot easier.