The flickering was so bad in my case that the pixels got stuck for some minutes when it happened.
When I connect my laptop to a projector, I can select an individual window, or at least I used to be able to select a window and just project that. However, now when I try to select the window, as soon as the mouse cursor gets near the selection button, the button disappears!!! It has been driving me absolutely insane.
But it's especially obvious when it dims itself based on ambient room brightness, I can actually see the vertical refresh happening as I move from a fully bright room to a dim one.
Weird green tints for no reason.. bubbles that take so long to inflate, you think your tap was dropped. Round edges that no longer fit the text content. Stupid ellipses at the edges of wrapped text. And all the functions that now take two taps when one used to do it. Text rendered on top of text for crying out loud! Whole view panes clobberin* each other. WebKit is a mess of wasted black bars where menus were hidden. Multiple flashes of white and black between content changes. It hits Apple apps as well as trashing third party layout.
Too many defects to list.
Headline: Apple celebrates 50th anniversary by burning down 40 years of human interface knowledge.