I think there's a lot of variability in user experience ... that doesn't bode well for M$... NO consistency and a history of problematic upgrades. I've heard both good and bad at about a 50-50 ratio. .. not too stellar. I've even heard problems upgrading from VISTA which is supposed to have the highest success rate.
Most will get Win7 with a new computer. . . . esp if they have XP. Who wants to reinstall all their programs too ? That can be a problem if someone has several "upgrade " disks and can't find the original program install disk.