The simplest answer is I will not upgrade any systems currently running windows 7 to windows 8.
The complex answer is that there is little to no value as long as windows 7 exists. People can site new and enhanced features, increased performance, a better complete experience, and a myriad of other extras. Now that the nerds in the room are the only ones left listening, here's the truth. We are not the target audience for this, and it is going to fail hard. Why, three points.
1) The UI is atrocious on anything but a tablet. We can cope and learn to like it, but the business world won't. A laptop can outperform, outlast, and be priced cheaper than a tablet.
2) The MS store integration, and additional locks. I'm sure some of us saw Windows 7 prior to launch. Do you remember some of the security "enhancements" didn't show up in beta like it did in the release? 8 promises some additional lock-down, and we haven't even seen what's actually going to be there.
3) Where for art thou, Apple? MS is trying to be Apple, and windows 8 exemplifies all of the backward steps they are making. They want a slice of the software action, and with successes like Steam and the Apple (not to mention the xbox live arcade) they have proof the concept will work. In addition to the software, the more recent hardware changes are making it look like MS is trying to gradually change the ecosystem (rather than being "evil" and changing their business practices). On top of this, they are trying to create a unified OS on multiple platforms. They are making one model fit three very unique unique platforms by force, rather than integrating features and slightly modifying thing to fit their respective targets.
So three general reasons why 8 is destined to perform poorly. It's my hope that it eventually gets rectified, and if history serves its purpose windows 9 should take the good parts of 8 and make it worth looking at. Nearly two decades of development, and MS OSs are still only viable every other incarnation. Shameful, but a trend proven time and again.