Okay so the taskbar is horrible as ever (meaning since it's been changed for the worse, it hasn't become better at all).
1) You can't move it to the bottom of the screen, or anywhere else.
2) Trying to drag an icon grabs all icons at once, and doing so has completely no effect. This is an utterly meaningless thing to have implemented.
3) To drag an icon, you first need to drag it to the right, but dragging it to the right would make sense for making a shortcut on the desktop. Which brings me to (4)...
4) You can't make shortcuts on the desktop. Let me repeat that, for emphasis: YOU CAN'T MAKE SHORTCUTS ON THE DESKTOP. I mean, honestly, why?
5) The start menu is still fullscreen. Totally overkill.
6) No apparant way to browse software installed on the pc.
7) Taskbar and top bar have no right-click menu. It feels like something is missing, because in Linux' nature, everything should be customizable and therefor needs a menu to do just that.
8) Speaking of the top bar, why can't you move it somewhere else, too?
9) Why not merge the top bar and taskbar into one, like Windows does so brilliantly?
10) The rightclick menu for an icon (on the taskbar again) has too few options. When the application isn't running, something like properties seems missing. When it is running, maximize/restore/minimize seems missing. Also no way to open a second instance.
11) The top bar fades between the application name and it's menu. Confusing. There's enough space and all the reason to keep the menu in view all the time.
12) Maximized applications have no visible restore/minimize/close buttons (only invisible ones, made visible by hovering the top bar). Confusing.
That's it for now. Back to Windows 7 again, which does all of these things right.
Disclaimer: I'm not looking for a Windows 7 clone! I'm looking for a sensible GUI. KDE is not a sensible one either, it's bloated and the start button (on the keyboard) doesn't even work. XDE is fine, a bit "too classic" to my taste, but much more sensible.