I think the problem (once again) is that Microsoft made the mistake of telling people what it was doing, rather than just releasing it and getting a pile of celebrities and adverts to say "wow - now my desktop is swooshy! Why have an iPad 3 when you can have a Windows 8".
I kind of agree, but then again, there are folks complaining that Microsoft is being too secretive wrt Windows 8. Anyway, Microsoft wants Metro apps to be ready when Windows 8 is released, so they have to release something before the actual release. They could release it just to devs, I guess, but it would leak, so what would be the point? Second, Microsoft does want feedback and they've made alterations based on user feedback (feedback that isn't of the , "What you're doing is totally wrong" variety). And they need the feedback to get bug reports. Unlike Apple, Microsoft doesn't control the hardware; they need to run the OS on many, many hardware configurations, of which they control none. Apple needs their OS to run on 6 or so hardware configurations, all of which they control.