I think I'm half-way through my 1st playthrough (cleared Rail City and Foundry, explored almost everywhere), and here's my feedback.
I enjoy the game, I enjoy the difficulty of combat, I enjoy the setting. But it has a big imbalance in terms of info available to the player.
TLDR of Underrail's problems: the game is balanced around players reading the wiki, forums, and other out-of-game sources. It is unbalanced, and sometimes downright unfair, to normal players who only rely on the information provided in the game.
Example 1: infused leather
The Beast is the most recent quest I finished. My character is light-armored, so when Bernard started talking about Supersteel, I didn't care. I asked him to make one, not because I needed it, but because I thought it might start some new questline. It didn't. When he said it takes a few days, I left. On my way out, I passed by Leonie just to see if she had high-quality chempistol components, as a long shot (she never does). I then left Foundry, not planning to come back anytime soon.
So there's this new improved leather useful for light armored players available with her, but had I not read the wiki, I would never have known. The game doesn't mention it in-game like it did for Supersteel.
Am I supposed to mouse over vendor inventory every time I REvisit a merchant, just in case they have some unique blueprint that the game added silently after a quest? No. That's not fun. That's the very definition of tedium, the sort that would turn a 10/10 game into a sour experience.
Example 2: Core City quest lockout
I hadn't started Core City, mainly because I was worried about being locked out of things, having read that starting a quest (not even finishing, just accepting) with one company locks you out of all the others. Any normal RPG gamer tries to do as many quests as they can, as this is mainly how game developers feed prepared set pieces to the player. So they are likely to accept the quest from the first company they talk to. I looked it up on youtube, and the line starts with "Do you have any work available?" (not "Can I bind my soul to your company forever?"). At no point, in ANY of the dialog with the company representative, does the game indicate you're locking yourself out of every other oligarch questline. The poor gamer (playing blind) finds out when they leave, go into the next building, and talk to the receptionist.
If that had happened to me, I would have been upset by this unfairness. Imagine if you're a plumber, and get a job fixing someone's sink. Then you leave, and try to find another gig, and the government tells you you're not allowed to be a plumber for other people anymore. Only the original homeowner. You weren't warned about it, you didn't sign a contract, but it's being enforced. You'd think they were retarded, wouldn't you? Well that's what this design decision is.
Conclusion
I get that the game doesn't hand-hold the player. But the difference between "hard but fair" and "unfair" is whether the game provides the player with the tools and info to succeed on their own, like Dark Souls does. And Underrail frequently fails at that.
Btw, reading wikis IS hand-holding, so you can't claim some sort of "hardcore game" cred by not putting info organically in the game, instead leaving the work for people who edit the wiki.
If you insist the current game design approach is fine, then I suggest for your next game you embed the wiki into the game as an official in-game manual, updated along the game patches, and provide buttons to access and navigate it in-game. It would be bad design, but an improvement over what Underrail is like now, because then no one can 100% claim they felt cheated over info the game didn't give.