Like many others I like the idea of Folder Tabs, but have come across many irritations. The one about actually adding the Folder Tabs is mentioned a lot. Having to choose an item within a folder to select that folder is not intuitive and is actually pretty poor.
My issue revolves around where the dock is positioned. I have 2 monitors and if I place the dock on the right-hand edge of the left-hand monitor normal tabs work fine, but the folder tab appears on the second monitor when it's closed. It may be that using a dock in this way isn't advised because of how the two screens interact, but if normal tabs work surely folder tabs could too?
Also, it would be good if you could choose to not show the background for a tab or all tabs in a dock. Because the theme I have chosen is fairly dark the background for the tabs is a semi-transparent, graduated black. Fine for Object Docks own icons that have white text, but in folder tabs the icon text takes on the windows setting, which is black. This makes the text difficult to read regardless of what colour I choose because the background shows through.
I think the Folder Tab option could be a really, really great feature. But if it can't be made to work properly just ditch it. Having incomplete or buggy portions to the software just tarnishes the whole thing and I really like Object Dock.