The syntax is basically the same, but they took out or changes some things. For instance, the 30k stacks mod had four things removed/moved, like the cooking pot which was in teh blocks.xml. The ammo had a change, regular bullets changed, for instance 762bullet, because 762bulletball, and steel ammo no longer exists (I think it because AP or HP). In my terrain mod, it had an error from there no longer being a sidewalk terrain block.
For other things, there were materials that no longer exist, or there was significant overlap so it would take a redesign, i.e. for the quality effectiveness mod.
Oh and the icons have a new folder structure.
Move the icons to:
UIAtlases/ItemIconAtlas
hope that helps.