Since this review touches so much on the difficulty, "super guides" and such, I'd like to highlight this video. It demonstrates just how masterful the world design was in this game, and that comes from it letting the player
see something in practice rather than simply hear about it.
http://www.youtube.com/embed/rcrdJD8whfEIt actually reminds me of another interesting observation that one of the most effective tutorials ever put into a game is the first screen of level 1-1 of Super Mario Bros for the NES. When you press the control pad, you move. You can't pass/defeat the Goomba unless you learn how to jump: Press A. The first block is spaced in a way where you are likely to hit it and discover ? blocks have things in them. If not, you'll probably bounce into the next few blocks when testing out the jump mechanic some more. The next block contains a mushroom, and the row of blocks above makes it hard to dodge. Once you run into it you learn that they make you grow, and when you are hit you realize it gives you an extra "chance" so to speak. From there, you're free to explore the wider world. A brand new player may not get the mechanics the first time and end up dying a couple times, but it's still designed so the player can't move forward unless they are comfortable with the fundamentals.