If you think not, then who you gonna call? DM Busters?
LOL!

Very nice.
There are two types of game balance in a RPG. One is between the DM and the players, and the other is between the different players.
The first type is what Gary Gygax invokes when he describes Monty Haul and Killer Campaigns - games where the balance between the threats and rewards that DM provides the players with has broken down. One of the great failures of AD&D - in my opinion - is how Gary spends a lot of time talking about how AD&D means to set right these extremes, but precious little in achieving it. Indeed, there are times when what he said has been misinterpreted and caused styles of gaming that are not what AD&D was meant to be.
One example is in regard of the scarcity of magic items. AD&D is not a system in which magic items are rare! Why do some people believe it is? Because Gary spent some time discussing how
at low levels they should be rare. This was then extended to higher levels which is quite against how the game was demonstrated in modules and other source material later.
The second type is invoked when Gary writes in the foreword and introduction to the Player's Handbook about how he was balancing the classes. In this area, I believe, he was quite successful. Yes, the low level magic-user is possibly a bit too limited, and the very high level magic-user is too strong, but in the main levels that AD&D was written for - 4th through 10th - the game works very well.
There are parallels between D&D and Squad Leader/ASL. With Squad Leader, you had one of the most successful wargames of all time - if not the most successful. (One source posits 200,000+ copies sold). However, with each expansion, the rules got more confusing and contradictory. Eventually, Advanced Squad Leader was released which completely rewrote the rules to be make sense as a whole.
D&D - with oD&D and its supplements - was in a similar state and so AD&D should have been like ASL. Unfortunately, I don't think Gary was up to the task of integrating everything successfully. There are too many areas where there are still contradictory or incomplete rule systems. Consider the monk's reduced chance of surprise. How does that integrate with the d6 surprise system? The answer is: it doesn't. At all. Initiative is a mess, especially as regards spellcasting, and then you have a small section about helmets which doesn't flow with the rest of the rules at all!
However, the major structures are there and you have an eminently playable game.
Cheers!