It's been a long time, but I can definitely remember my fave thing that changed going to 3rd edition, was the streamlining of all the rolls.
Starting with 3rd edition, everything you had to roll was roll HIGH, instead of high for this, low for that, etc..,
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I distinctly remember the rules getting easier to manage, allowing more focus on actual gaming.
That was at the start, then tons more stuff came out, but you know, you dont' have to use that.
Many fond memories of 2nd edition though,
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I still have some of the rulebooks around too, and of course a ton of Realms, Ravenloft and other world stuff that's 2nd edition.