Its size makes it easy to carry in a bag or even a pocket. On the surface it's a bit bigger than a credit card.
It is also self-powered and allows easy access to stored data.
The Router function is also very useful to me in my dorm room, there was an Ethernet cable. By plugging this device above, I finally WiFi in my room after a few minutes of setup.
After a few days of use I won.
My only complaint is that it creates subfolders on my memory card when I insert it.