The only thing I really hate is that you can accidentally resize full screen windows if you drag from any corner. This also disabled the drag-from-corner shortcuts that I used a lot. In iOS 18, you could use the corner shortcuts as well as split view and slideover. Now if you want to use corner shortcuts you have to completely disable multitasking. And if you use multitasking, you have this whole mess of a billion ways to multitask, when realistically on an iPad Mini I NEVER want to resize windows. I just want split view and slideover, and nothing else. With all these complex interaction modes, it would not be a huge deal for Apple to just add adjustments to how deep you want to multitask. I don't want the menu bar, the corner resize and the traffic lights, because they're too small to use and too easy to accidentally invoke.
Now you can drag down from the top right corner to do control center, drag down from the top left to do notification center, drag down from the top middle for the menu bar, drag either corner diagonally to resize... it's a bit too much. And turning off multi tasking means I lose the one thing I like: slideover.