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While I prefer the desktop Cube myself, I can see why some will prefer the Desktop Wall, and I found it was actually quite well executed.
As for the Wheel Switcher, it has officially replaced the usual Alt-Tab method for me (I've remapped it so it's Alt-Tab instead of Super-Tab). It's fast and visually pleasing, and reminds me of the original Tomb Raider inventory system. All it's missing is some kind of discreet audio feedback...actually, that is a neat future feature for Beryl: the possibility of adding sound effects. Sure, they'd have to be off by default (as they would drive most users crazy), but for me using subtle SFX would add to the experience.