While I like the idea of the new taskbar, I find its implementation to be sub par. I'd like to see some sort of indication of what's running. Maybe it'd be too similar to the OSX dock, but maybe an arrow, or a glow, around currently running apps would make the taskbar much more useful to me. Or have all of the running apps line up on one side. The random mix of running apps/shortcuts throws me off a little bit.
That said, I really really like the ability to hold my mouse over the icon, have the preview window open, hold my mouse over the preview, and then have that transition to the whole screen. That part of the implementation is absolutely amazing, and very intuitive. They just need to organize it better.