Been into DF for a year or so. Despite the UI and the fact you need a wiki to play the game to the fullest, I sort of use DF as a litmus test of how hardcore people are about RPGs, SIMs and stuff like that.
Because it truly is a thing of beauty, and the graphic tile sets people have made for it make it playable by most anyone that has a willingness to explore mechanics instead of just having simple ones fed to you, and has an active imagination and a love of the game NARRATIVE as much as the graphics.
This is what DF looks like with a tile set. The pic is from before the last major revision.

DF does what no game I've found yet does: it treats mechanics seriously, as something worth almost all of development time, and develops mechanics beyond what almost any other dev house envisions. That's why the game will never be done, but that's why I'll also never stop playing it. In a perfect world, all dev houses would put the kind of time, love and thought into their games that Tarn Adams has into his.
And what's seriously mind blowing is that, at its core, DF is quite simple. Text files, tags and that jazz. What's not is how he's assembled it all, and how far he lets the simulation and detail run. When you consider how many millions of dollars go into just making a guy in a 3d environment look cool and do simple interactions with ladders and terrain....DF is the exact opposite. It's what ~8 years of work can produce in terms of game mechanics.
DF is only a few megs as a download. The game files it can produce can run into the GIGs. That alone should tell you something about the game.
So yeah, if you've heard about it, I suggest you let go of your graphical/learning hang ups and just try. The tile sets bring the game up the 8-bit level, and the wiki + the forums will teach you everything you need to know. The DF forums are reasonably mature and welcoming to new people. Just be ready to LEARN a game as opposed to just PLAYING one, because DF is that deep.
Also, if you really wanna know why people love DF, you have to read about Boatmurdered. Even if you don't play the game, it's a hilarious read.