The biggest draw with this game so far is the diverse possibilities allowed through character creation.
Yes, it's quite nice in theory but has some issues.
1) Reloading your game over and over until you get an appropriate birth sign for your character archetype is ultra lame. I heard the creator was
-ing people by advertising it as a feature or something if you donated for it, but I'm not sure if that's changed by now.
2) Questionnaire is a really cool character creation method but generally won't make a huge difference if you don't go all-out with a reference chart.
3) Most of the "feats/perks" list are pretty shit. But I'm cutting it some slack here because I think it's one of the first few games that experimented with such a system in an RPG and pre-dated D&D 3E even.
So basically the part of CharGen that has the most impact on your character is the part which is randomized.
Incursion: Halls of Goblin King is still the RL with the best CharGen to date.
Now, as far as difficulty goes and since Crawl was brought up... ADOM comes from the old school "difficulty" design which are constant "knowledge"/spoiler checks.
Basically, the difference between how the two approach difficulty differently would be.
ADOM: A Medusa enemy who kills you instantly (no-save) when you enter Line of Sight, unless you are equipped with a Mirror Shield, which then instead kills the Medusa immediately. Either you know this fact and Medusas are trivially easy or you don't and there goes many hours down the drain, but at least now you have the knowledge for the next run.
(this is actually a Nethack example, but it fits ADOM)
Crawl: A Medusa enemy has the ability to petrify you. Petrification doesn't kill you instantly, but leaves you open any enemy attack while it wears off over time. But first, it has to penetrate your magic resistance, and even if it hits, since it slowly petrifies you over time, you are able to use consumables or maneuver yourself into a better position to escape the effects and your ability to pilot yourself through these sort of "danger checkmate" situations is what separates the good from bad players.
I personally prefer the Crawl style because I don't really like the sort of "Knowledge = binary difficulty" gameplay anymore but I suppose each person's mileage may vary.
Nethack is considered really easy once you memorized all those little factoids, but ADOM is still considered challenging because there's significantly much more of those you have to keep track at the same time and I think going for the "Best" ending is more of an exercise in masochism than an accomplishment, but then some people beat Wizardry 4...
I think the biggest thing that kills ADOM for me is that having played Crawl, I can't go back to the interfaces of most RLs anymore including this one. I don't even know why the hell you need a specific keypress to dig your ears or some shit like that (well, I know why in the game but I need to know what drugs the creator was on when he implemented that)