The difference when compared to 3rd edition is that they admitted it. You can't play 3e the way you played earlier editions and get the same results. Yet people still carried on playing the same settings and pretending nothing had changed. So they could do so now. Disliking the 4e rules is fine, but insisting that the 3e ones were like earlier editions in a way the 4e ones aren't is ridiculous.
Not IME. I play in both a 3.x and an OD&D game. Although 3.x adds a lot of new options, the fundamental gameplay is virtually identical.
We've noticed only three significant points of departure:
(1)
Sleep is crazy powerful in OD&D. It effectively ends any low-level encounter.
(2) Turning is incredibly powerful in OD&D. A 2nd level cleric can
automatically turn 2d6 skeletons, for example, and there's no limit on the number of encounters clerics can turn in a given day. The result is that undead encounters are fast-tracked for obsolescence. (This was changed in AD&D1.)
(3) The lack of a mechanic for handling searches requires significant adjustment. (But, of course, this was gone by 1976.)
I've also used 3E modules in OD&D and pre-3E modules in 3E. The result supported the fact that
encounter design, not fundamental changes in gameplay, is the difference most people describe in 3E versus pre-3E play. (Modules played the same regardless of the edition you were playing them in.)
Conversely, I've run
Keep on the Shadowfell (or sections of it) in both 4E (three times) and OD&D (twice). The result here was a radically different experience.
This is unsurprising, frankly. 4E is a game explicitly built to support a very different style of play and it's fairly trivial to notice that the core gameplay has been radically altered for every single class.
Any printed adventure *must* to some extent be a railroad. Perhaps one with lots of branches and tracks, but still a finite number. Adventure paths only exacerbate the issue by forcing assumptions as to the resolution of previous adventures.
This assumes that "branches" and "tracks" are the only way to design an adventure.
They aren't. And, in fact, they're a poor way to design a non-linear adventure whether you're writing a professional game module or prepping your notes at home. I recommend
Don't Prep Plots and
Node-Based Scenario Design.
If you design situations instead of plots, it's actually quite trivial to design non-linear printed adventures.