I loved the 1e DMG. It taught me everything I needed to know in order to be a DM. Heck, I may even go back an re-read it now.
I have been running 3e since 2000. The 3.X DMG just lacks the ability to train new GMs. It is a great toolkit, yet that is all it will ever be. It lacks the cohesion, advice, and gumption of the 1e version.
The culture of 3e says that the "game serves the rules." This is inherit in just about everything that Wizards produces, and the DMG is not strong enough to teach beginners that the "rules should serve the game." (Reproduced with permission of Psion.

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Do not get me wrong, I enjoy 3e. It is a great game to play. Yet it sucks to run unless you have a handy computer and a program like E-tools or HeroForge to help make stating NPCs easier. The rules are so intensive for a GM, that excessive work is required to challenge players, who are very proficient in crafting effective characters. A simple NPC build gets wiped every time! This leads to less time preparing for other areas of the game....like plot etc.
To put it in better terms, I GM'd 2e for 3 years and never burned out once. I GM'd 3e for 4 years and burned out 3 times.
Yet I still GM 3e. I just love DnD too much to quit, even if 3e is not really DnD. However, for the very first time, I am considering trying a new system. This will probably be Castles and Crusades for a more DnD-like game, while I will go with Blue Rose for the ladies.
Just my thoughts. I know a lot of people truly enjoy 3e. It fits the current generation of computer gamers and allows a lot of customization and cool abilities. I just think it lacks the soul and character it once had.