One of the most common requests on the Skype community forums over the last year and a half is some (any!) basic configuration options for the UI.
There's no way to get a properly compact view, there's no way to set the color of the bubbles, and the support for high-DPI screens is abysmal.
In fact, once I started looking into it, I found a whole batch of UI problems with the new "improved" 7.0 UI, which I shared on the forums and then gathered into a handy blog post:
Skype 7.0 - A new entry for the User Interface Hall of Shame?
The 7.0 UI feedback thread is the longest one on the community forums, and can be found here: