I like UI. I sort of think of UI as like the surface connecting the user and the system - if it's smooth then it blends in with the experience, but if it's bad then it creates friction (wasted effort). In some games, the fun overcomes that friction, but as time goes on and the fun decreases (and maybe the friction even increases with your experience and knowledge of the game!) the fun level can drop below the friction and the user gives up. A Tale in the Desert is the poster child for this - a game with a fantastic concept that you're likely to get sick of fast because of the UI.
In Dwarf Fortress' case, maybe I'm crazy but I think the basic UI is pretty simple. It's easy to conceptualise and operate it and the problem is more that it's not explained clearly and that makes it harder to get the concepts down. For the most part it's pretty easy though:
d - designate areas, for tasks that operate over a certain space like digging or chopping down trees
b - make a building
p - place a stockpile, an area where the dwarves store stuff
q - interact with buildings
v - interact with creatures
k - look at stuff
shift - hold this down to move the cursor/screen around faster
I mean, the keys are pretty arbitrary, but they map to game concepts in a fairly simple way, and there's a little key reference over to the right all the time unless you turn it off with tab.
Getting started is easy, too. Simple checklist:
1. Food?
2. Water?
If you have those then your fort will sustain itself fine (not necessarily optimally, but your dwarves won't die) and you can just sort of build on it from there.
The pitfalls of the game's UI for me are more the things it deals with badly after you've mastered the fundamentals. Stuff like your fortress dropping dead because your food stockpile was full of barrels of plump helmet seeds so they wouldn't store anything else and all starved to death, or the chores involved with making large numbers of similar rooms or digging out mineral veins (that last one being mitigated by DFhack). It's really easy to get bogged down in repetitive tasks and it's easy to have something going wrong and not really know why.
Another big issue is that the game engine works in 3d but the 2d map is just not good at showing it. I don't know if there are any good ways to improve it - it does a good job for what it is, but it's such a limiting format.
It's a delightful game, though, and really worth checking out. It's very eccentric, but that's just added charm, right?
