As a windows management device its very handy but I find as a UX solution it quickly falls apart due to its half-baked integration.

On the 11" iPad (I cannot speak of other devices) I can only have 4 stages on the sidebar at any one time. If I have 6 open it hides the other 2 from the user. I resort to using the usual swipe-up gesture, defeating the purpose of stages altogether.

I can swipe in from the left with apps open to pull up the stages but do so from the homescreen and it still opens the increasingly useless widget dashboard.

If I have the maximum of 4 apps open on one stage I have no idea what app is what on any view bar the swipe-up gesture, again defeating the purpose of stages.

A better solution would have been to have the stages minimise to the dock in place of the 'recent apps' bit. Each stage would be similar to a folder icon with the 2x2 app grid showing you what was open on each stage. You've then got more screen real estate to work with and no UX gesture repeats.