The best way to switch between apps on an tablet or phone device seems to be the bezel slide in gesture. That said, there are many issues with implementing this approach. The foremost being that apps requiring long screen gestures and interactions such as games will invariably cause users to accidentally switch away from the current app.
This is why having a full bezel to bezel gesture across the device's screen required to switch apps is more appropriate. That said, this system invariably loses out on some of the best aspects of the single bezel slide in approach, such as dynamic feedback illustrating that one app is being switched for another the moment the bezel gesture begins. This can't be applied to the bezel to bezel approach without losing the reason for using it in the first place, preventing interruptions to the current app session from accidental bezel slide in gestures.
This is why I propose a hybrid. Require a full bezel to bezel gesture to switch apps but only beginning the dynamic feedback at the midway point. This could be implemented as a gradual fade in of the next app below the user's finger at the midway point or, to conform more to Apple's design language, having the current app begin the recede into the background at the midway point followed by the next app sliding into place on top.
I'd like to see this approach implemented in the iPad as the current 4 finger gesture limits the functionally of apps to 3 finger gestures or less.
