Trying to actually answer the question without making value judgments...
More defined traditional fantasy archetypes as pc's
More reliance on DM judgment than having a rule for everything
More abstract combat
More dangerous magic (Haste ages, Fireball with blow-back, etc.)
In terms of adventure and campaign design, at least prior to Dragonlance, it took greater influence from Sword & Sorcery literary sources than Epic Fantasy sources, and many of the rules - training, natural healing, learning spells, etc. - fit the episodic type campaign rather than the epic quest type campaign much better.
Those are just what I can think of off the top of my head. I like all of the above, so I like 1e. I know a lot of people dislike all of the above, probably framing all of the above in more perjoritive terms, and therefore like 3e better. Different strokes...
R.A.