I played it a few months back for about 15 minutes and quit with such a huge disappointment in myself; I just couldn't translate the abstract graphics in my mind.
A few days ago I gave it another whirl but also grabbed a graphic pack and suddenly everything became clear. Oh, those are trees, that's a miner dwarf, that's a kobold, that's a mushroom, etc, etc.
As soon as I was able to understand what I was looking at then I spent the next 15 hours straight figuring out the controls and gameplay mechanics (and it was FUN to learn). I am in love with the game and it just totally blows those million dollar projects out of the water with the depth and detail of gameplay.
I can play the game now without the graphics pack thankfully so I don't have to rely on them. Anyone remotely interested in the concept of the game but turned off by the graphics (or lack thereof), it's totally worth it to figure out. And once you do, the amount of entertainment you can get out of Dwarf Fortress far outstrips the majority of games with a $50+ price tag attached to it. Can't stress that enough... if you like the concept, it's worth it to figure out. Awesome game.