2E AD&D is, to me, the "inertia" edition of D&D -- TSR knew they had a good thing going, and their primary goal was not to do anything to screw it up too badly. The 2E rules are basically the same as the 1E rules with most of the kinks worked out and rough edges sanded down and with a few very modest "improvements," most of which had already been present as common house-rules for years. If you already were playing AD&D, 2E gives you more of the same, in a bit user-friendlier package.
The problem is, AFAICT 2E offers very little to make the game appeal to those who weren't already playing it -- it's smoother and easier to understand than 1E, but it's also bland and flavorless; the infectious "magic spark" of Gygax's prose and the amateurish but full-of-life art that really draws you in and makes you want to be part of the game is almost entirely absent from 2E, replaced by a level of conservatism and self-referentiality -- you weren't supposed to question the reasoning behind things in the rules or implied setting, you just accepted them because that's how they've always been; likewise innovation and doing things in new or different ways were frowned upon and extrapolation from and accretion on top of the existing rules, structures, and formulae was the expectation (symptomized also by the ever-increasing prevalence of "fluff" over substance -- instead of giving you new and interesting monsters we'll give you a couple pages of fluff about the existing monsters, even though you'll never use any of it in a game).
1E AD&D was vital -- lots of people hate Unearthed Arcana because they think it made too many changes to the fundamentals of the game, but miss out on the fact that the game in those days was vital enough that such changes could be made; 2E OTOH was completely staid and ossified, and only the settings showed any hint of innovation or vitality (but they were all separate and distinct from one another to the point of being essentially separate games -- you couldn't really use a Ravenloft adventure in a Planescape game, or drop your Dark Sun character into a Birthright campaign).