I'm only forced to use Windows occasionally but the things that always annoy me when I do are the lack of: Column View, QuickLook, spring-loaded folders, hierarchical view, calculate folder sizes in list view. The worst is how folders sort on top, so you can't just type the name of a file to jump down to it if there's a folder with a similar name. The whole tree view is so weird with how it treats folders as this special different thing.

I do not understand how people can get serious work done with Windows Explorer, but I presume that's just because I'm not used to it.