SmartScreen is functionally useless, though. All it provides is a UAC warning for unsigned code, the likes of which through a legitimate user has clicked an untold number of times for perfectly legitimate reasons.
The issue is that due to the high costs of getting a certificate, a lot of legitimate software for Windows is still unsigned.
I know several large FLOSS projects, with hundredthousands and millions of users, that ship only unsigned binaries, telling their users to turn off SmartScreen.
If Microsoft would have used a GPG-like mechanism, or provided certs for free, it would look very different.
Here's a video where the malicious file is executed. Nothing immediately seems amiss: https://youtu.be/DD9CvHVU7B4?t=1m43s