Well, I've come to the thread late, but I do have some things to say so I'll say them.
I loved D&D when I first stumbled upon that purple boxed set. I was perfectly happy playing an elf as my character class. To this day, if I'm going to run a game for a complete group of new players, I consider dragging out the D&D Compendium. We originally rotated DM's, and many of us owned the older supplements for the D&D game like Greyhawk and Blackmoor, and it was all fine by us. Put us in front of a dungeon and we'd clean it out.
I switched over to AD&D mainly because my game group did. And it was like a revelation. Race and class combinations. Rangers. Jesus, did I love rangers. To this day, whenever I start playing a new campaign, I consider playing a ranger just because my most memorable character was one. (And strangely enough, he had two swords...we worked out a compromise that I basically used the left sword like a shield in game terms, which was fine by me...I wanted two swords solely because I thought it looked cool, not because I was going for damage): granted, I think a lot of people identify rangers with RA Salvatore, but that's okay, a lot of people identify them with Aragorn. To me, rangers are Robin Hood. AD&D served the purpose I asked it to: it let me play a game and pretend to be someone else. To be honest, I've never been the subtlest player and as a result, a lot of the rule problems people have spoken about weren't obvious to me...I played characters who either filled enemies with arrows or closed with them and got messy. AD&D did fine by me for this purpose. As a DM, I found it harder to run, but not so much so that I was particularly disenchanted with it.
I'd definitely say that AD&D was my 'gateway drug' towards other RPG's. I would never have played Champions, GURPS, or Palladium if I hadn't played it. It's funny to realize that I played AD&D, both first and second edition, for as long as I did. I played that game in one form or another for almost two decades, from the beginning of the eighties to the end of the nineties. I have horror stories, of course, and there were elements I didn't like (especially when the second edition came around...some of the race and class choices they made annoyed me) but in general I played and enjoyed it for quite some time. But I did drift away, and there were several reasons for that drift. The first was time: I couldn't play as much as I wanted to during and after college, especially when I moved around as much as I did. The second was that I'd come to enjoy having more control over my character's starting abilities than I felt I was getting from AD&D...point buy systems had become the games I was most often playing. The third was that I felt a bit put off by the people who were playing AD&D. Now, I'm aware that snobbery and elitism are silly when one is talking about RPG's, but people who believe that a rigid legalistic mindset is somehow worthwhile when talking about one's hobby have always seemed to be putting the cart before the horse to me, and that was all I was finding. (Admittedly, that's subjective, but I can only speak to my experiences and the way I was thinking at the time.) I play games to have fun, not to have a ten minute discussion of weapon speeds, which is what was happening to me a lot more than I was comfortable with.
So around 1996, I more or less stopped playing AD&D. I came back to the first edition rules for a memorable summer in 1998 or so, when one of my earliest game groups (and the longest lived) got back together over the course of a few months and more or less wrapped up our characters. And it was fun, and we enjoyed ourselves. And that was it for me and AD&D.
I would not be playing D&D, and possibly not playing RPG's at all, right now if not for 3E. Not only has it brought back a lot of the simplicity I liked in the original game while keeping the options of AD&D, it's brought back players, so far as I can tell. I enjoy the game immensely, and to me, that's what the games have always been for.
As to superiority or inferiority, I can't see any reason to make that judgement. I liked AD&D. I like D&D 3E. I enjoy having skills and feats, I think it's something that helps keep options open. I vastly prefer multiclassing as it now stands to the old multiclass/dualclass rules. I think, however, that without the evolution of the game marketplace fueled by AD&D's existence over the years that these features would not exist, and therefore it's like asking if I think grandpa is inferior to me. He's my grandpa. AD&D is a big chunk of my past. I'm not going to rank on it, nor am I going to pretend that I don't think the new version meets my needs now. I find it more easily introduced to new players, more streamlined, and I prefer the mechanics of the new game.
I'm not going to make an inferiority/superiority judgement. I am, however, going to keep playing 3E over the old rules. I liked them, they had their time, and now I've moved on. Not without fondness, but definitely and completely.