Using "spoiler file" or wiki, will give you a rough overview of the creature's strength and ability, weapon effectiveness, etc. This is helpful but is not enough to win.
To win you must understand deeply (grok) all the different mechanisms of the game (hunger, prayer, sacrifice, alchemy, intrisics, etc) and then have a strategy.
This guide allowed me to ascend :
This is counter intuitive but the early game is much harder, once you have found the right items, identified important scrolls and potions (about finishing gnome mine & sokoban) the game becomes much easier. And if you are well prepared everything beyond the Valley of Death is kinda boring and "easy". For a first ascension, it is probably wiser to chose an easy class (valkyrie, barbarian, knight, wizard).
Key strategy for the early game are : using your pet to identify cursed items, to not level up too quickly because the generated monster will become too tough, when in a desperate spot engraving "Elbereth" with your fingers might save you a few times, praying at the right time, etc
A full game with a successful ascension is about 20-30 hours. However you probably need 50-100 hours of failed attempt to learn the rope first. And it can be frustrating at times because even if you know the game better, it will take some times to make a breakthrough and survive the early levels.
Lastly if you really want to learn fast, play on a public server, and when you are in a very tough spot, you can (at least you could) ask people on #Nethack on Freenode for advice.
In the end, the game is very satisfying, because even if there is a big element of luck, once you know the game well, this is your skill as a player that will determine if you live or die, and this is really rewarding.
I played quite a few hours of Moria (never killing the Balrog, but I never really was that motivated to "win" - I generally enjoyed finding new items, and discovering/learning "all" the spells. This in the older versions that included fun things like "Genocide"). I've also played a bit of the various Angbands, but I keep feeling that the stuff they add/change tend to make for an inferior game.
I really thought NH and Moria were more similar -- I think now that my initial dislike for NH was based on this misconception (NH is indeed a poor Moria, but it might be a great game if not viewed as a "version" of Moria).
My experience after discovering the game was one of being overwhelmed. Every single keyboard button has multiple functions, there's so much stuff happening and you're just stumbling around in a world whose rules you don't understand. (Like real life.)
After some time, I've dived into the spoilers file and gave it an extensive read. I realized that it would have taken years of playing figuring all this game mechanics out. And that even when spoiled, the game remains a lot of fun. (Again, like real life.)
What remains are fond memories and the realization that I'll probably never finish it in my lifetime. And I'm ok with that.
So yes, it's complex and complicated, but rewarding.
There are also spoilers all over the place on the internet, namely on the Nethack wiki, that'll answer any question (literally, any question) about the game that you have.
But every time you play and die, you'll learn something. The learning curve is the game.
Select one item:
a - Long description of the game and commands.
b - List of game commands.
c - Concise history of NetHack.
d - Info on a character in the game display.
e - Info on what a given key does.
f - List of game options.
g - Longer explanation of game options.
h - List of extended commands.
i - The NetHack license.
To get started you really only need to know two commands. The command ? will give you a list of the available commands (as well as other information) and the command / will identify the things you see on the screen.
For software that runs in the terminal on a unix system, putting such instructions in the manpage is the appropriate thing to do. I don't know how they do it on Windows, it's quite possible it's more obscure there, which would be a shame, because more people on Windows are uncomfortable with TUIs.
The GUI version has menus that feature the same content that you get with '?' in the terminal version. For the console verson on Windows, you'll have to read the manual.
When I started with NetHack in the 80s on the Amiga, I wouldn't have had any chance of playing it if the Amiga version didn't feature menus with all the available commands showing also the keys.
It's probably a bit easier to learn than Dwarf Fortress, but not by much.
It is an absolutely rewarding game once you make it past the first entry point, though.
Personally I found it to become a lot more fun once I started using spoilers, as there were so many things I would never have found out. The only slight negative is that I have since become obsessive about trying to identify things by all available methods, that costs time and is a bit boring. But that's my own choice.
And I'm a completely hack and slash player -- I've ascended 15 Valkyries I think (and some Barbarians), but I'm utterly useless as a weaker class that needs to be played with caution. I did manage a few wizards that got lucky early on, they become all-powerful later.
I knew a guy who quit drinking for a week so that he could ascend. So there's that, too: don't play drunk.
So that'd be a yes. 301 gold pieces to the priest, not 300.
You can control the curve by choosing how much to self-discover/look up online. Many of the secrets will take a good while to discover by yourself.
Make sure you play it with a good terminal character set but don't go for graphics that would spoil it.
This game is the definition of "gameplay is more important than graphics"