I've been doing this for a very long time -- way before even Win 1.0. Every time a vendor
comes out with a new OS, some are excited, and others are upset that they have to learn new ways of doing things, and that some old ways no longer work. Just to give one example every change to the UI (and the "start" button -- or "start" button analog) in recent
Windows releases has give rise to cries for the old way to be put back, and rants that the
new mechanisms will never work, and will never be used. Roll the clock forward a year or
so past RTM, and most of the complaining has died down: old muscle memories have been
replaced with new; new shortcuts and tricks have been discovered -- we move on.

MS is rigorously sandboxing WOA, Metro, and legacy apps from each other IMO to keep the complexity under control. With the memory of Vista fresh in their minds, they want to keep strict control over all the W8 components -- especially all the hardware and apps coming from non-Microsoft sources.

Flying my airplane above 60,000 feet, the ability to do everything on a W8 device that I
can do on my iPad, and yet still have access to the full panoply of Windows features is
immensely compelling.

I'm interested in all these early reviews, but I won't put much credence in negative ones
until 6 months to a year after initial release