I play 3e. Started by playing 2e. (I'm 25).
A friend of mine is storing his 1e collection with me (he moved to canada... girl... bad ideas... now he's back... long story)
I've been looking through his books from time to time. (love the MotP)
I think the difference between 3e and 1e is just the feel of the books, the way they smell (sit down! no fart jokes till i'm done), the art (especially the full page stuff and the covers - loved that in 2e).
Like I said, I have never played 1e. So the things I mentioned seem to add up to a different expereince of D&D, and not just rules-wise. It looks like a different game. Less pointy, more castles, more tunnels, more "chivalry".
I've heard it said that the 1e DMG is probably the most usefull and chock full of info of the 3 (4?) editions of D&D DMGs. From what I've seen I think I agree. One of the things about 1e is that it seems to have so much content derived from our own world's histories and myths. 3e seems bland and generic in a comparison of that kind of content. Just the cover of the DMG alone makes me want to boil my current campaign down to the gleefull dungeon crawl evoked there.
Even 2e has it's own feel that takes me back to the days of old, when we were but scratchy voiced yutes hiding our treasured rulebooks from our well-intentioned but ,alas, close-minded parents.
No, I won't ever play 2e again. Just won't... ok, maybe.