I, like you, have never seen nor heard of a similar problem as you are describing
Squiggles/lines/colors/circles
I can advise that many people have had issues with the upgrade on many different computers as a result of......
#1 Peripheral hardware attached to the computer. USB Dongles (Bluetooth, other RF or IR wireless devices, etc.,) So if you have anything like that attached you might want to try removing everything extraneous and just go with a monitor, USB Keyboard and USB Mouse and see if that provides any relief.
#2 Third party software, running at startup (although I would have thought that a safe mode boot would have resolved most of those). There are some instances in the case of third party security suites, where even a safe mode boot will not completely disable them or their associated drivers and uninstalling them completely has been necessary to get past a related problem.
Reverting back to your previous operating system if of course always (at least for 30 days post upgrade) an option, although many people have reported less than optimal results after having done so.
Sometimes it works like a charm and sometimes..... not so much.
I would certainly make every attempt to make sure I had all my critical data backed up before resorting to that option.