It's just different, really. Windows has kept things relatively similar for 17 years, and it's hard to re-learn these things after so many years.
There's plenty of room for improvement, but Windows 8 is the first step for MS along the path to a new way of computing that was laid down by mobile devices. When tablets came around, they started changing how we compute, and it's likely that our desktop systems will be shrunk down into mobile devices at some point in the future, and more and more things will become connected and unified; Windows 8 just provides the framework for MS to keep up as the changes happen. I think that Windows 8 does a good job of balancing new and old; it's pretty easy once you get used to the charms bar and get the start screen customized the way that you want it. I'm actually thrilled to have a full-screen Start screen that gives me a nice clean and organized way to get at the multitude of apps that I install, and having my appointments, tasks, etc. on my start screen as live tiles.
I also think that people's attitude will change a bit when developers start making new and innovative apps. We've got new UI options, and I have no doubt that there will be some brilliant apps to enhance entertainment and productivity. I'm excited to see what Windows Blue will bring, too.
Just before Windows 8 I was starting to think about creating a more unified experience with my mobile devices, PC, HTPC, and so on with network and cloud apps, and when I first booted up Windows 8 my mind started reeling at the potential. I can't wait to see what the future brings!