First, to skurtchasor's rant.
I don't think D&D is a bad system, per se. For what it's trying to do (hack and slash strategic combat simulator) it's pretty damned good. That being said, I do think it is a poor game to introduce newbies to roleplaying with. Not because it's a difficult system (though it is, terribly so - on top of the rather significant amount of numbers involved to be successful you need to have a pretty thick knowledge of the system to avoid making bad decisions in feat and spell selection that can cripple your character down the line).
Anyway, it's a poor game for a few reasons.
1) The genre material it draws from isn't very familiar. D&D fantasy is a breed in and of itself - it doesn't look like traditional epic fantasy (Tolkein, etc), and it doesn't look much like traditional Sword & Sorcery fantasy (Conan, Elric, etc). It might bear superficial resemblances to them, but in reality it's its own thing - consequently it can be difficult for new players to really relate. If I tell you (the clueless newb) "Hey this is a great game, it's a fantasy world bla bla bla" and you think of being Aragorn from Lord of the Rings, or Conan or Tomoe Gozen or whoever... you are going to be sadly disappointed. That's not to say that D&D fantasy is a bad thing - it's just different, and often unfamiliar. Other RPGs exist that draw from far more familiar genres that might be more easily recognized by the prospective player.
2) D&D is very much focused around the campaign. For a new player perhapst not sure if they want to do this roleplaying thing, it's an awful commitment. What's more, D&D games tend to take a bit to "get going" - it's slow, and frankly it doesn't make a great first impression. There are other RPGs that are designed to be played out in a single session (My Life With Master is a wonderful one).
3) D&D is difficult. Yeah anyone can learn it - but frankly it's an obstacle to be overcome. The difficulty can end up being rewarding - but for the prospective player, it might be best to stick to something a little more lightweight, where the investment vis a vis comprehending the system is a lot lower.
So now that we've got my counter-rant out of the way - can anyone post here with successful stories of new players (new to roleplaying, not to your group) learning the ropes with D&D? What about stories of new players being alienated by D&D?
Now Dethstryke, heh you picked a topic that's of particular interest to me (and a few others on here): The idea that system doesn't matter. Frankly I disagree, and here's why. (Note: I'm just paraphrasing what Ron Edwards and others at The Forge have said about the subject... )
Look, yeah any GM and group can get any system to work for any paritcular game. But the fact is, that it's going to take a lot of work. Try using D&D 3.5 out of the box for a game focused around a bunch of politicians - barons and whatnot - in the local realm. Yeah with work you can make it work, but you're going to have to do a lot of retrofitting with the system - D&D as designed is intended to be used for hack-n-slash dungeon crawls, not tense political debate. The premise behind System Does Matter is simple: wouldn't it just be better to have a system designed to support the mode of play you're looking for? That way instead of spending however many mental cycles retrofitting and house ruling D20, you can just get on with playing and enjoying yourself.
Looking forward to replies and thoughts.