Windows 8 is an enormous gamble and the firesale upgrade price reflects that MS sees it that way. They are all but bribing users to upgrade, and if you want the Windows improvements from the last 3 years, this is your only route. This is the first time there has been a serious discount for an upgrade license for Windows ever. (Although maybe the Win 3.1 upgrade might have been only $50... I don't recall any more, but in that case it was well worth it).
With Windows 8 Microsoft is foisting a whole new UI paradigm on desktop users who didn't ask for it and mostly don't want it. Yes, you can still use the desktop mode, but I'm betting a lot of non-techie users will just suffer with Metro because they have been conditioned to unquestioningly accept arbitrary awfulness from computer software. I doubt 95% of computer users ever go outside of the web browser and Office applications... and no matter how awful the Metro implementations of these apps are (I imagine IE in Metro isn't much different, but other apps?) they'll just deal with it. After all, they learned how to use Word, one of the most arbitrary and capricious pieces of software this side of Lotus Notes.
I've seen it in person too many times to believe that most non-technical people don't realize software could be a lot better and that it doesn't have to be the way it is. And in a lot of corporate environments, even if they know, they can't do anything about it.
And the only reason MS is pushing Metro on non-portable device users is to jump-start their own app store, because I'm sure they are drooling over the idea of taking a significant cut out of every software sale like Apple does. They are drooling so much that they are willing to risk antagonizing desktop users in order to get it, understanding that a lot of people will just think "this is the new normal" and go along with it, because they don't have the knowledge or experience to realize they have some say in the matter.
This is not a bash on users... a user should not have to be an expert unless he wants to be, but Microsoft is counting on being able to strongarm these users to suit Microsoft's needs, not the users'.
MS is years behind in the tablet and phone markets and Surface doesn't look like the iPad-killer it needs to be to give them a foothold in a market where they are currently all but irrelevant. Ditto phones. MS can't coast on the biennial desktop/laptop upgrade cycle the way they used to because a huge chunk of money spent on computing devices is going to devices where MS doesn't (currently) have a decent entry.
Meanwhile, a lot of users will needlessly suffer with the angry fruit-salad of Metro and hate it, but just take it as the new "normal". If that weren't true, Office would have actually gotten better over the last 15 years.