Biggest thinga are IMO save/load for online games and also a rollback of the campaign changes from 1.33.
Though, thinking about the latter: Fucking hell, Blizzard. Fucking. Hell. It should never have come to a situation such as this in the first place!
Yanked from the “other” site, section 3.e:
3e. State of the Game FAQ
WTii’s videos Warcraft 3 Reforged ONE YEAR Later… and TWO YEARS Later… as well as THREE YEARS Later… goes over some of these points and makes a number of observations and highlights.