I come from a background of ADOM, Bard's Tale (the originals), Doom, and Phantasie. I've played almost every major DOS RPG, and probably a good many minor ones as well. I grew up gaming on a Commodore, and still love mine, even if the disks are bad. And I play Mega Man still.
I kept hearing about DF, and ignored it for about a year. Then I finally broke down and downloaded it, well into the 3D era. Spent more time reading Boatmurdered, Nist Akath, and the other huge stories, and that's what got me interested in it.
Even so, it took me 6 months off and on to get to playing it, because I had trouble with the interface. Something I never had a problem with even in other Rouge-likes (pretty much only had to look up the obscure commands in those, like 'w'ipe face).
I think the biggest issue is the UI for me. The ASCII is fine, and actually a bit better than most similar games (though I saw one that used highlighting in different colors as well as the stock 16 color ASCII character set, which was neat. Never could get it to work though).
Why do I need space to exit some menus, F9 for others?
Some automation would be nice as well. We already have an auto-tanning job brought up. It would be nice to set a minimum animal limit, and have auto-butchering jobs for any non-pets non-cages animals we get. Automate fish cleaning, cooking of raw, freshly butchered meat, and dumping of vermin left by cats.
It would be nice to be able to read notes via 'k' as well, or even when you use 'q' to access a given building (like levers!).
The troubles with micromanaging dwarves is another issue, one that kills most of my forts (or dwarves. I've taken to keeping maybe 20-25 dwarves civilian, and activating the rest. Most of whom die horribly, because I treat them like the US Army treats their soldiers. Actually, since my military dwarves get free coffins in a nice hallway, I treat them better (but I'm not bitter about what they did to my grandfather with 2 Purple Hearts, a Silver Star, and 36 years of service, no!).