I know this is such a little nitpick for a huge project like this one, but every time I see ReactOS screenshots I notice that the taskbar looks off. Comparing this [1] screenshot from the article to this [2] random Win98 screenshot, the start button and app buttons seem to have different margins, padding and dimensions.
Again, it's such a small thing, but I (and I guess other people do as well) tend to focus on this kind of graphical details. I wonder if it's easy to fix...
[1] https://reactos.org/sites/default/files/imagepicker/23908/Ex...
[2] http://www.guidebookgallery.org/pics/gui/desktop/firstrun/wi...