I usually dislike doing the "breaking down quotes" thing too far past the original quote, because it starts getting incomprehensible, but I'll give it a go.
I actually disagree about many of those points.
In AD&D multiclass characters have all the powers from their classes. That's very different from 4e system.
I don't see what this has to do with the stress of single-classing over multi. They're not identical, sure - but single-classing was the dominant form in 1E, IF (stress IF) you used the rules as they were in the PHB, and you capped demi-humans at those abysmally low levels anywhere from 3rd to 9th.
XP from monsters is a small contribution in AD&D. XP from treasure is actually scaled down when the challenge was easy.
True, but monster XP was written with minor adjustments for amount of hp. In 2nd edition D&D and Basic D&D, monster XP was an absolute static amount. It still is more reminiscent of 4E to me than the sliding scale of 3E, which I don't like very much when it comes to figuring out XP in larger parties, or parties where there is a level difference.
Saving throws are very different in 4e, however. The chance of success is flat and does not depend on class, level and ability score. They mostly represent durations excepts in few cases.
I agree, though race does affect it, and it is and can be used for more, especially when you run into things that class or level just should not matter for. I do think about experimenting with altering it for ability scores in some fashion, though -- but not by ability modifier, since the range is kind of narrow.
Magic items are listed in the PHB. Players are encouraged to come up with wish list... quite different with how things work in AD&D.
One difference to that was the lack of customization of characters mechanically in the original 1E books, or in the Basic D&D books -- meaning that a Wizard who liked daggers but found a better magic staff was all too happy to switch, because likely he wasn't any better with daggers than staves (unless he didn't have the weapon proficiency or something). A fighter with a glaive dropped it in favor of the Bastard Sword -- but on the other hand, DMs in my experience frequently customized their treasure in dungeons, or they dropped hints about what could be found in certain adventure locations so that the players could make up their own minds.
In 3E, in the default case, whatever the DM put in a session didn't matter because they usually sold it so they could buy whatever they wanted. Magic items found on location were more like commodities or art objects than actual rewards. I have heard of examples on these forums of DMs who clamped down tightly on buying and selling of magic, but the majority of DMs apparently did differently. 4E discourages it so fervently that it's a jarring experience for players used to getting good value out of selling magic in 3E, and they accuse the DM of shafting them out of treasure, until you point it out in the books.
Well, combats in my 4e games are exceedingly long... once again very different from my experience with AD&D.
Here's one where I have to differ just on results at the table. I will say this: 1E combats are still shorter than 4E combats; I can't get around that, because of the fewer options available for non-spellcasters, and the simplicity of 1E spell wordings that leave so much open for DM adjudication. my 4E combats though are somewhere between 3E's lengths and 1E's lengths, assuming the players have written down their powers on their character sheet beforehand, or are using power cards, and aren't doing a lot of page-flipping. Players do take more turns in a combat, just like they did in 1E, and they do move around a lot more at lower levels, moreso than 1E or 3E combined, and maybe slightly less than my 2E games i used to play in 10 years ago. But I've never had an experience where an equivalent combat in 4E took longer than it would have in 3E. In fact, in 3E, we'd take for a 6th level combat involving maybe 10 to 15 combatants total, about two hours. The same would take us an hour to an hour-and-a-half in 4E.