I've been playing this a bit, courtesy of tpb.
I put it on the hardest difficulty, and I really recommend it as the default, it's been suitably challenging and I've had a few prisoners die so far, I've reached the 4th nebula level, each nebula level introduces a new variety of enemies and I think it increases their health in addition, and it feels like there's a strong variety of enemies although I'm starting to reach clones of previous enemies with new attributes.
Although if anyone can tell me what the difference is between the scribe and elder scribe I'd love to know, because they seem to behave exactly the same.
Dying & rolling a new character is minimally punishing. The biggest drawback being losing your ammo stash in my opinion, although you lose fuel, food, torpedoes, warp cores and anything you'd gathered in the current ship, but these are largely irrelevant with some barest amount of planning.
I'm not too sure how much further content the game contains, I presume I have about a day or two of gameplay left before hitting the credits screen, if that's the case, then this is pretty short for a rougelike, looking at BoI and Enter the Gungeon as examples of length and replayability.
Speaking of replayability, there's hardly any variety from one life to the next.
The level generation changes, but you could have not died and you wouldn't have noticed the difference.
Unless you receive a severely crippling perk like smoker but then you might as well just suicide and re-roll? I suppose it depends on how much you want to roleplay as someone who's trying to survive and escape this nebula within the game?
It's a good game, nothing that wows me I think. But good enough to warrant playing.