A major difference between Windows Device Manager and Gnome's Device Manager is that the Gnome version concerns itself with properties, which are in a way messages, rather than drivers. Windows allows you to view a device, determine which driver is installed, and find out if the operating system thinks the device is working correctly.
Gnome Device Manager does not relate to a device driver, and the presence of a listing in the hardware list does not indicate that the recognized hardware is working, or can even work at all under Ubuntu, or even if its recognized. However, Device Manager does do an extensive scan of the hardware in order to determine the hardware's capabilities.
If a device on the PC or a peripheral is not working or not working correctly, it's useful to find the hardware in Device Manager just to find out what Ubuntu actually knows about it. Then taking the hardware's name and searching for it in Google or on popular Linux forums may provide a fix, or at least somebody who can commiserate with you.
Will Gnome Device Manger evolve into a robust hardware manager? It's too early to tell, but right now it's a powerful and handy utility for viewing and identifying the hardware devices on a PC.