I don't play OD&D. I tend to play the 1981 B/X D&D and use some of the 70's supplements and Dragon articles to flesh things out. The one main reason I don't use OD&D is availability - you can still find Basic sets for cheap on the Internet and in used bookstores and the reasonably compatable 1979 and 1983 sets are available on the Internet for cheap, I already have three copies to spread around the table. If the OD&D books were still easily and cheaply (and legally
) available, that would be my system of choice. Why?
It's the tabula rosa. It is presented in a very different light that AD&D1... From page 4 of Men & Magic:
As with any other set of miniatures rules they are guidelines to follow in designing your own fantastic-medieval campaign. They provide the framework around which you will build a game of simplicity or tremendous complexity — your time and imagination are about the only limiting factors, and the fact that you have purchased these rules tends to indicate that there is no lack of imagination — the fascination of the game will tend to make participants find more and more time. We advise, however, that a campaign be begun slowly, following the steps outlined herein, so as to avoid becoming too bogged down with unfamiliar details at first. That way your campaign will build naturally, at the pace best suited to the referee and players, smoothing the way for all concerned. New details can be added and old "laws" altered so as to provide continually new and different situations. In addition, the players themselves will interact in such a way as to make the campaign variable and unique, and this is quite desirable.
Plainly put, it was not designed to be a comprehensive game. It was designed to be the starting point, with the referee and players exploring the limits of the rules and then going beyond them with their own creativity. What rules are there "get out of the way" of the creation of the new.
Criticisms of completeness are off-base. What people are really missing is the melee combat rules (There are actually fairly detailed naval and aerial combat rules in the set.) and I suppose this is understandable given the percentage of most rpg rulebooks that are taken up by combat these days. There not there simply because the game was originally designed as supplement to Chainmail. It's like criticizing the DMG because it doesn't have all the rules from the PHB in it. History has shown that the game is flexable enough to take on a ton of different melee rules and perform quite well, whether the Chainmail, Greyhawk or Holmes rules, or the more esoteric like Melee (GURPS' great-grandaddy) or Sword and Claw Law (Rolemaster's antecedent) or any of the various rules from the Judes Guild or Arduin Supplements. While it was originally designed to be tacked onto the Chainmail game (or maybe vice versa) there's really no reason why anyone couldn't use whatever combat rules they wanted with it.
I'm convinced that criticisms of organization are viewing the game through the lens of 4 Supplments, 2 sets of miniatures rules, an introductory Basic set, various other accessories, and volumes of magazine articles that came out over the next 6 years. The original boxed set, taken on its own is quite well organized despite the sheer amount of stuff crammed into its ~110 pages of rules.
The sheer exuberance and excitement of coming up with something new nearly drips off the pages. It really is an inspirational read.
I don't want to say that OD&D serves a different style of gaming, because that's not true. Really, the OD&D rules serve any style of gaming. However, the OD&D set serves a different attitude towards rules. People in general used to be a lot more laid-back regarding rules than they are now. It came from war games. You adapted rules to fit the scenario. If you wanted to have Indian war elephants in a game that had no rules for them, you made something up. Really that's all Chainmail was - Fireballs duplicated the effects of catapults, Lightning Bolts duplicated the effects of ballistae. The rules were a creative endeavor between the referee and the players as much as the campaign world was. In fact, I'd argue that there really wasn't any distinction made between the rules and the campaign world, as evidenced by the quoted passage above... the rules were how the particular campaign world worked.
I realize today's gamers, especially D&D3 players, want things much, much, more codified. They don't want the grey areas and rules gaps of the older games. (And frankly, I find there are far fewer rules gaps than most people believe.) I just don't find it as fun. As a player, I don't feel like I have as much "wiggle room" to come up with creative solutions to problems. As GM, I feel like I've been turned into an automaton. I just prefer wide open spaces and unexplored vistas in my rulesets.
R.A.
) Plus, a lot of things said in the 1980's while keeping a company afloat won't apply the same now. I always try to put in mind the context a statement was made in in addition to what a statement says. 
