The NeHe guides get you up and going quickly and provide a base for easy experimentation. That alone makes them hugely useful, I believe. The code is horrendo

The NeHe guides get you up and going quickly and provide a base for easy experimentation. That alone makes them hugely useful, I believe. The code is horrendous and there's often a lack of explanation, but it's very easy to take the code and play around with it. They're certainly not the thing to read if you're looking for best practices, but they give you the ability to hit the ground running.