Despite graphical flaws, the game itself is great, it's a alot better than other roguelikes, read on
Huge variety
Dungeon crawl has a massive variety of everything, from species to backgrounds(classes) to items or even magic, this means that all players, regardless of preferences, can easily get into the game, from the quick learning average humans, to the fast centaurs or that mindless and redundant battering ram that is the troll, or half dragon Draconians, classic bloodsucking vampires or the (you saw this one coming, didn't you?) Orcs, backgrounds range from the everyday fighter to berserking zealots or the popular Crusader hybrid , all coming down to the one with the largest choices : Mages(nine, more than any others), you've got the elementalists of the four elements, Necromancers, summoners, you name it, hell, even the god choices are numerous
Extremely clear
Them Crawl developers spent alot of time making sure that everything is clear enough that even illiterate people can understand things without needing for spoilers, the tutorials don't have anything in them that isn't clear, you probably don't need to research on a certain enemy, their descriptions provide what you need to know about anything
Skill, not luck
Crawl isn't a gambling session, even if you had the best luck in the world, only skill will get you far, sure, some times a little bit of luck is needed, but for most of the times, skill wins, if you had knew how to escape from a dangerous situations, you would not had that dead character over there, likewise, not knowing how to properly manage skills is just as bad, but from your mistakes comes know-how, slowly but surely, you'll slowly climb up that ladder to victory, but even then.....
High randomness
Each Crawl session is different, with map layout randomly decided by the game and monster/item placement also randomly placed, this means that you can't simply know how to do everything and breeze through the game, each session requires you to find new tactics and face new challenges, even veterans will fall, giving big replayability to the game
Easy interface
The long, mind numbing and redundant chores are automated and made easy, for example, autoexplore means you can easily explore the dungeon without having to repeatedly press the directional buttons until they break or something, long distance travel is also made easy
Replayability value
Because of the huge diversity of the game, Crawl is fun no matter how many times you play, there are infinite playing styles, random dungeon layouts, surprises, large numbers of species and many backgrounds mean that you'll could launch this fucker up any day
Link : http://crawl.develz.org/wordpress/downloads