The ability to edit/define one's own shortcuts is fine; but the command ("cloverleaf") key can't be used in the shortcuts definition pane, nor is there a way to remove the pre-defined shortcuts that use this. Instead they have to be defined via the System Preferences Keyboard settings, and this can lead to conflicts/ambiguities.
For example I want to use Command-1 through Command-8 to cycle through the views Right Side - Trimetric; the first three are predefined, but Command-4 and -6 are assigned to Zoom Window and Zoom Home, respectively, and these can't be changed, leaving these two doubly-defined (and with ambiguous precedence).
Having a unified way to define/edit shortcuts that use the modifier keys - perhaps Control and Option as well as Command? - would be very handy.