Yes, it's black and white without using the system's accent color. There is actually a bit of feedback on Skype asking for theming. I know as a developer it isn't hard to implement system colors.
I'm a little puzzled about Microsoft's theming direction in general. They are being rather inconsistent. On one hand they are making some apps and Windows 10 dark (but using greys instead of black), some white and not following the system theming that was introduced with Windows 8. Windows 10 has had some theme hacks as well but went away. The new store in Windows 10 for now can be theme switched by Ctrl+T.
It seems like they are just going a little bit darker and ignoring user choice in the matter. But grey is depressing, black is sophisticated.
I just want a black/white empty space theme that can be user toggled and work for all apps.
Back to the original topic, it is a little less jarring opening up Skype now.