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The 'wall' should really come in a 2x2 configuration by default, not just as an option. I really don't see the point of putting them on a line as shown in the Beryl video, wasting all that space and showing them so small. Here is the same effect on a 2x2 configuration (on OS X):
As for the wheel window switcher, is that really a *good* example of usability? I find it about as useful (that is, not much) as Vista's: some windows are partially covered by others. Basically, just like the wobbling FX used every time a window moves or opens (*), that particular video screams "look at what I can do" more than "Beryl Usability", at least to me.
(*) How is wobbling anything (windows, drop-down menus, even freakin'tooltips!) a good thing, from a usability point of view?
Windows deformation when you drag them around gives an interesting visual feedback. It's also a good visual representation for Maximize/Minimize. I personally don't have it when a Window opens, though, and I believe that this is default (I don't remember changing it).
That said, if you don't like it, just turn it off. It's as simply as unchecking a single checkbox.
As for the Window Switcher, Windows are only partially covered when you have *lots* of them open...however, you can change the shape of the ellipse in order to minimize this, if you want.
I do agree with you for the default screen configuration...however, there are issues with the number of desktops with KDE, this might be why the default is the (safe) 1x4 configuration.