I wouldn't say my upgrade to Windows 8.1 was smooth.
The laptop first crashed soon after the upgrade. When I connected my external HDMI screen, Windows blue screened and pointed out the NVIDIA display driver as the culprit. I disconnected HDMI and updated NVIDIA drivers to the latest version, but now blue screens started to occur when attempting to open the NVIDIA Control Panel. When it didn't cause the computer to crash, it still failed to open with an error stating that no NVIDIA graphics card is currently active. I checked the Device Manager, but all it said was that NVIDIA GeForce GTX 780M is operating correctly. That's even though it clearly didn't: I tried starting a game to make sure, and the frame rate, which should be about 100, was between 1 and 2. I didn't even try HDMI at this point.
It turned out the problem was that the upgrade to 8.1 disabled the Intel HD Graphics 4600 driver. I had to download a new one from the Intel Download Center. After installing the new Intel HD Graphics driver, the NVIDIA graphics also started to work fine. I've now been able to connect my external HDMI display, and the game shows a normal frame rate.
Here's to hoping that's mostly the end of Windows 8.1 upgrade troubles.