Just downloaded it tonight, so I've only played with it a bit and I like it very much. I plan on putting it on a USB stick, but I think it would be handy to have Q-Dir open in the same drive it was on when it closed or to be able to specify where (what drive) the panels should be when first opened.
Fast full view switching. having folder tabs for the single folder view. there are times when I need to view as many files in a folder as possible, yet want to easily be able to drag and drop these files into another folder. I would love to have all 4 folders appear as tabs so I can drop the file onto the tab to copy it, of course this also means that I can reopen these folders with just a click for fast full view switching.