Originally Posted by The Hundred Gunner
Is it more customizable? It depends what you call "customizable." If you mean on the level of changing wallpapers and the locations of your task bars, they're about the same. If you mean being able to mess around with open source software and command line utilities, then yes, it is much more customizable than windows.
That depends to some degree on your desktop environment.
For instance, in KDE, I have much more control over the desktop "picture" than in Windows: I can, for instance, use a realtime weather display, an interactive globe, a progressively growing "virus", an animation (which Vista Ultimate had, but I think MS removed from 7 on?), or an interactive Mandelbrot fractal viewer; not just a image or slideshow.
Also, I don't even have a taskbar in the traditional sense. Instead, the notification area/system tray is a box on the right of my screen, and the task manager is a plasmoid (KDE widget, essentially) in the corner. There is no Start or application launcher button, that is handled by middle-clicking anywhere on the desktop.
I've not used the other popular DEs (Gnome, Cinnamon, Unity, LXDE, et al.) enough to compare, but KDE is incredibly easy to change drastically:
This was done without any command-line or non-default software use as well, other than a small plasmoid to remove the 'cashew' menu.
As you alluded to, the interface is far from the only customizable aspect of Linux, as well; the user can change a great deal about what the system does and how it does it, especially if using a more advanced distro like Arch or Gentoo.