Microsoft has fumbled a ton of announcements and products, no doubt, like all tech companies have. Long Horn was atrocious, the failure to deliver the Courier was stupid, IE 6 was horrendous. But Apple's Newton, printer line, Lisa, "puck" mouse, Final Cut Pro X, all not great. Google's Wave, Buzz, Orkut, Android Honeycomb also not great. These are just the "big three," but you can't point fingers for long without finding examples in every camp. Demo fails in the presentation? All tech companies have great demo fails on Youtube. As for "freezing" the marketplace...Apple seems to have warmed up the tablet market to nice and toasty. Microsoft is freezing...nobody but itself. They are a serious underdog in this space. They needed to do something. This was the right move. It bridges the gap between laptops and tablets and takes advantage of Microsoft's strength in the desktop space.
You're right, though, the proof will be when these hit shelves, and no, I don't think this is ghostware. Microsoft is done with the software and these are in production. I'm guessing there won't be a long delay, and a lot of other things can go wrong (too expensive, poor battery life, etc.). But you're missing part of the point.
Microsoft is setting the bar for a Windows 8 tablet. Its hardware manufacturers now have one standard they will have to outdo...and they will. Hardware manufacturers aren't going to stop making tablets, and if they can't have iOS (and they can't), then they will go with either Android (an excellent but still immature OS) or Windows (very mature and ubiquitous).
Competition gives us better stuff.