One minor bug I found while putting it through the works is when you are actually editing the file upload inside the content builder portion. In the upload settings, you can specify an action if the file exists. If you select "Rename existing file" first and then try to switch to another option, it does update to the new option unless you cancel out and re-enter the editor.
Not sure if this affects all OS systems... I am on Mac Snow Leopard.
Regards,
Brian