Time to master the arts of combat and spellcraft. Time to wield the great sword while simultaneously developing one's stealth. And multi-classing certainly gave non-humans a unique set of abilities. But demi-humans already came with a fairly impressive array of racial talents, from dwarven toughness to elven skill at arms. And then there's infravision, an unnecessary throwback to when non-humans were dungeon-dwelling monsters because anyone who wasn't a player character was a monster, obviously.
And so in the interest of killing our darlings and finding gold where others may see only tarnished brass, we'll suggest here that OD&D just might have been the first time the hobby got elves right. Dwarves and halflings were a different matter; but elves were absolutely something OD&D did right, even if it wasn't the only right way to do things (there's seldom any wrong way to do imaginary play). Now let the gushing commence...
OD&D elves could switch between fighter and magic-user between (but never during) adventures, wearing armor and wielding weapons during one descent and taking up a cloak and staff the next. And once they got their grubby mits on a suit of magical armor, elves could wear it while acting as a spell caster. Awesome! But its value was diminished as early as the supplements, where a more traditional multi-classing, complete with armored spell casters, took hold, which begs the question: Why OD&D's way?
First off, it was easy. If you played as a fighter and got 1,000 experience, forget the division; everything went to the fighter class. Ditto when going as a magic-user.
But it was also realistic (as far as that goes). Spells can't operate through armor, and a magician needs their hands free for complex maneuvering. But magical armor is specially engineered to accommodate such energies, so a suit of mail +1 is no obstacle for elven thaumaturgy. At any rate, different strategies require different equipment. If heavy fighting is part of the plan, best to suit up and polish that sword. But with stalwart henchmen at the ready, going light and casting spells just might be the better option.
Finally, OD&D elves felt special; and this uniqueness was highlighted by the fact of its simplicity. Soon enough, too many additional powers were added, leading to even greater attempts to balance them all. But the mere ability to switch between two classes when others couldn't was more than enough to set them apart. Over time, things began to feel like a bloated bureaucracy badly in need of the streamlining B/X and BECMI literally brought to the table. OD&D needed more work, but it got its elves right from the start.
Elves are naturally magical, so most (if not all) eventually learn to cast spells. It's just something they can do. And like all races, they can arm themselves for more conventional fighting as well, because there's nothing more basic than picking up a nearby club and bludgeoning your enemies senseless. But magic allows the impossible to happen, making it useful and its practitioners in high demand. You can't play piano while kayaking down a raging river either; but it's cool to switch between them. That's elves.
Now to be clear, we adore AD&D; and for those desiring a more robust old-school experience, it's the cream of the crop. But for all OD&D needed to work out (dwarves and halflings spring to mind), its elves clearly delivered. Add the fact that they demanded superior strategy on the part of the player was old-school as hell and in keeping with the hobby's earliest traditions. If nothing else, it's another tool in the toolkit and something worth checking out if you want to challenge a group minus the fuss of later editions...