iStonsoft iPad iPhone iPod Disk Mode is an app that lets you use your iOS device to transfer data between computers. Both computers must have this app installed for this to work, though. Thankfully, there is also a Windows version available. So you can use this app to transfer files and folders between Mac and Windows PCs.
When you launch the app with an iOS device connected, you will see its name on the left. You can click on the device and then click on "New Folder" to start putting files and folders on it. You do this by either dragging the files onto the application window or by clicking on "Copy to device" and selecting the files or folders manually.
It should be noted that this application can't access the file system on your iOS devices. This means that you can't use it to download photos or videos from it or to put new ones on the device. You also can't access the files that you transfer using this app on your device, unless you use a file browser and find the directory where files are stored.
In short, iStonsoft iPad iPhone iPod Disk Mode works and it is a good way to transfer files. But you need to have the application installed on any computer that you want to use to transfer or retrieve files, and if you want to do that on a Mac and a Windows PC, you might need to buy the app twice.