I just installed a fingerprint reader in Ubuntu and after scanning my fingerprint into the system, I was able to login to Ubuntu using GMD3 and it works just fine. Access this by typing users in the Activities view to access the Users panel under Settings. Then enable the Fingerprint Login option to start the setup of the fingerprint login option. Choose which finger to scan and then place your finger on the scanner and move it around until the whole fingerprint is scanned. This works very well. At the password prompt for your user in GDM3, just scan the fingerprint instead and you will be logged in. This is quite painless and easy to set up. This does not seem to work at the password prompt in the terminal, but for what it does, it is very good indeed. I wonder how hard it would be to set up on Windows compared to Linux? My reader is a U.are.U® 4500 Fingerprint Reader. This works out of the box on Ubuntu. Give this a try yourself and see how you go with it. A great alternative to logging in with a password all of the time.
I tried the same hardware in Windows 8.1 and it was not working until I downloaded a driver and then I rebooted. Such a comparison between Linux and Windows. Linux has drivers in the kernel that work out of the box and it is easy to set up, but on Windows, it is harder. This should not be the case, but Windows does not have an open kernel and developing kernel modules is not possible unless you are a developer. This is really a shame, you need to sort through dodgy download sites to find one that is actually reliable and offers a proper download of the driver you wish to use. But this just requires persistence. The ability to use a fingerprint to log in to your machine versus a password is great.