The question I ask when I upgrading, is what can the new OS version do, that the current version cannot. As a network technician, I find Windows 7 ridiculously trouble free to image compared to Windows XP. And there are a number of other advantages, hence the reason to upgrade. With Windows 8, having read this forum and just general reviews on the Internet, I think I will give windows 8 a miss. It feels like a beta version of the product. In most businesses, a touch screen is just not doable, so I don't see the point of Microsoft's insistence on designing W8 to be optimal in touch screen mode.
glenn Barnas points about visual ability is a very important as many older people will have the same issue - can't see anything. its been interesting reading, but I will give Windows 8 a miss. The only major advantage of W8 over windows 7 is the ability to natively use virtual servers, but as neither myself nor any of my clients require this feature, I won't lose sleep over it. The only other thing I like is the boot time, but its not enough to make me upgrade to w8