Its really a great windowsI am using it, Specially the Access to Apps is the best option which I liked a lot, a friends of mine has installed windows 8 in his computer free of cost
It is said that Microsoft only charges you $10 to upgrade to win 8 if your win 7 was installed after the June 2012.
I don't think so. Win 8 will be totally a different system not an upgrade of 7. So the users will have to buy the OS costing its full value.