Currently, when you upload folders in the webinterface, i.e. a fotos folder with 300 subfolders, drive first creates all 300 folders (why?) and then starts uploading into them.
The problem is: If a download fails or you close the browser accidentally, and you have to continue the upload, you have no idea what has been uploaded and what not. So you have to delete everything and start from scratch.
It would be better if the upload happens folder by folder so you can see where the upload was interrupted and can continue right there.