I've just gotten around to using the new screen rotation option in Illustrator and I really love it. It works perfectly with my Cintiq controls. But, there is a quirk that is almost funny. As we know a tool like the direct select tool dracts a rectangular selection around objects. But, when the screen is rotated, the rectangular selection is also rotated! I was making selections and the marquee was very faint so I wasn't seeing it very well against a gray background but I was missing the anchor points constantly. Finally I stopped and looked closely at the selection marquee and that's when I saw it. The selection was marquee was on the same angle as the screen rotation. So I'm completely missing the points I'm trying to select because the marquee is not crossing over them. By comparison, if I rotate the screen in Clip Studio Paint then draw a selection, the selection marquee is not rotated so it is doing what my brain expects. If I then rotate the screen, the selection will rotate with the screen. That makes perfect sense. I just checked Photoshop and it has the same behavior as Illustrator. I'd never noticed because my workflow doesn't involve a rectangular selection. This is not a bug, but its definitely not how this should work because if you're drawing your rectangular selection the selection is not going where you're intending for it to go.
But, I love this rotation in Illustrator. Its smooth, and is bound to a key on my physical controller perfectly for fast, fluid work.