I'm disagreeing with waldo about the difficulty (never played those old versions mentioned, though). As far as I can see, DF isn't brutally difficult, and the rumor about that is misdirected and exaggerated. What it is, however, is massively filled with system of varying complexity, and learning them all in detail would be a massive task (I've ignored a number of them completely, and learned only what I believe I need to know about others).
However, you don't need to learn everything to run a successful fortress, as much of it is optional and other mechanics can be replaced with alternatives. For the fortress to survive, you need to get the basics to have a sustainable fortress, and unless you'll turn off sieges you'll also have to know how to keep the majority of the dorfs safe from enemies. After that, it's a matter of what you want to do with your fortresses: explore new (to you) mechanics, megaprojects, eternal bloodshed through sieges and raids (made difficult currently due to stress/work load induced by the former and fortress ending bugs with the latter).
@oldmansutton: No, with only half a dozen corpse cleaners you're likely to only rarely be able to let the civilians out onto the surface as new sieges tend to arrive before the cleanup from the previous one(s) is done, and when that "rarely" happens the whole hauler population will spend the time into the next siege hauling clothes and equipment. This assumes you're beating the enemy in the field or kill them with weapon traps (which I don't). Cage traps relieves some of it, and depending of captive disposal method, you can get rid of a fair bit of the hauling of their equipment.
Edit (hard to post and cover everything when other posts appear while you write yours):@brolol.404
- I think the current distinction betweem normal and "!" need activities is fine as a principle. If the overseer doesn't provide time off there should be consequences, but of there is time off dorfs should take care of things on their own (claim trinket when it becomes available, like clothes, and then pick it up in their free time, for instance). A fortress where dorfs are treated reasonably well should work better than one where they're worked to the bone (introducing Meet Friends! and actually do that would be great if Meet Friends wasn't available, rather than the current blanket Socialize(!) activity).
- I've seen dorfs go longer for preferred drinks and food than they'd have to. The problem here is probably not pathing but availability, with most dorfs just having a choice of "don't care" meals. The demotion of lavish meals doesn't help players used to the previous system when they were useful (they now have no mood effect at all in themselves, but can serve as "rare ingredient extenders" by mixing rare stuff with common ingredients. Of course, actually getting lavish meals prepared in an intelligent fashion at a fortress wide scale is currently close to impossible with vanilla DF). I think the reason for masterwork clothing the floor of dorf rooms is due to claiming a corresponding item of a desired material, but haven't investigated.
- Dorfs that have had a strange mood are immune to insanity. I had one that was tantruming and had maximum stress, but once I managed to get the finicky bugger to pick up a trinket of a desired material (wouldn't take anything else hauled), a slow trek towards recovery started. Unfortunately, the fortress was cut short by raid corruption when the stress level had improved from -100000 to -70000 (which is still extremely bad). I believe I also did other things apart from the crucial trinket acquisition to improve the condition of this starting 7 dorf, though.