Comment 5 for bug 857627

Can't agree more. The difference in colour and lightness added by the highlight is well within the range of variation among a typical set of icons displayed. A mental effort, or otherwise unnecessary switching, is required to detect the higlight. That reduces switching speed and is uncomfortable.

The same is true when switching among the windows of the same application. The fuzzy orange decoration around the window border is hard to see against the dark red background. There is added difference in lightness, but it only works (but not too well) for windows having white background. Dark-coloured windows are not distinguishable with this method, and the only highlight remaining in that case is border decoration, which is very weak.

 I can't recall a similar problem with any other switcher, including the old compiz switchers. For example, the way Apple does it, they darken the icon's background (icons themselves are transparent) and they add a white border around it, thus doubling the contrast. That makes the icons stand out very well, without making them obnoxious.

Another thing that contributes to failure in Unity's switcher, I think, is that it is heavy on decorations. Note that all borders have complex shapes and gradients, and that is distracting. That clutters the view and reduces the contrast, making it more difficult to find what you are looking for. Nick points out the same problem in the comment above; I totally agree. Clutter is not consistent with speed.