I really like the idea of the multitasking control centre and drag and drop but I am a bit concerned that the new slide over / split view app switcher will be more fiddly when trying to access apps not on the dock.
However I haven't tried the beta yet so I can't really make a proper judgment on usability yet.
I feel that something like the following concept would have been more intuitive whilst still keeping the same gesture actions. I also think it feels more natural to just swipe from the edge to activate split view and then drag to resize the app.
The only addition I would add is to include the same hovering dock along the full length of the iPad.
For example the different gestures:
1. Swipe from right edge = modified home screen app picker as shown + full length dock with drag and drop
2. Swipe up from bottom = hovering dock only with drag and drop (same as iOS 11)
3. Swipe up further = multitasker spaces & control centre (same as iOS 11)