As far as the OS is concerned, I think you'll see people continue to * very loudly in the echo chamber, while actual customers will make the transition without much fanfare similar to how Vista went. It's a change, and people, especially "power users", always * when things change. But it's really not that big of a deal. The desktop experience is something you can get used to, while the Metro side will be very compelling on touch devices (and keep in mind, within a few years desktops will be touch devices).

When it comes to WinRT the biggest issue I believe is just developer burn out. In a vary short period of time we've already been through three XAML stacks (WPF, Silverlight and Silverlight for the Phone). That's a lot to learn. Add to this all of the other "essential" APIs we've been through with (WCF, ASP.NET MVC, EF, LINQ, Rx, etc.) and it becomes hard to get excited about another API to learn, especially one that's "just another XAML UI stack". For this reason I think for the next year you'll mostly just see Phone devs working on WinRT apps while the others continue on with what they already know and use. Over time that will change as the marketplace starts to demand more Metro apps, especially if Win 8 tablets become "in demand" at the enterprise level much like iPads have.

My take is that Microsof has a difficult year ahead of them, but long term I believe they've made the right choices.