It has been over a month now on W8 and it is very solid. No complaints, and I have adjusted to many things that bothered me before. I would now list the only cons as the following:
App Access - You really need to put some effort into getting this setup. For most people they probably won't notice because of desktop icons. Me I hate desktop icons and a cluttered task bar so this is more important. Take for example the calculator. You can't just click start and jump right to it anymore, you need to locate it. The fastest way (without pinning a shortcut) is to hit Windows Key + F, click on Apps, and type in calculator. Kind of annoying, but a small price to pay for the great new start page. Like I said common things you pin to start and/or taskbar and no worries.
I really wish I could swipe in the panels for things like Music. Going to the bottom to drag the scroll bar left and right is annoying. Give me a mouse gesture so I can swipe left and right like I do on my phone. Clearly that is the point, give all devices the option to do this.
I'm irritated that I have to go into the desktop background dialog and navigate to the folder containing the image I wish to use in order to change my background. When looking at an image you can right click to get a set as dialog but it only contains lock screen and app, no desktop background.