Vista was and is a piece of shit. I haven't had to reinstall my Win7 in 2 years. Very stable. I'd avoid Win8 for a year in order to give MS some time to work out the bugs. However, I've read here on BHW that with an online coupon (available somewhere) you can upgrade to Win8 for $15.00. If I had Vista, I would definately do this cheap upgrade. If WinXP, maybe, maybe not. if Win7, I would hold off.
Also, those with interface objections, my experience with software developers is that they force you into the GUI they want you to have, and make you figure out how to make it look the way it used to. In this case, I think you could probably change the new look of Win8 back to something that closely resembles Win7.
If you think about it, it's too great of a risk for Microsoft to try to force people into the new GUI. They could just get stubborn and reject Win8 like they did Vista. Some people still refuse to upgrade from WinXP. They see no reason to. From their perspective, WinXP is "good enough". And Win7 is a much better operating system than WinXP, so people could be even MORE resistant to upgrading to Win8. There's no reason to Win7, and if they pollute Win8 to the point the everyone hates it (like they hate Vista), Win8 could completely flop and MS would create another generation of die-hard people that refuse to upgrade.
So, that's my long-winded reasoning to why I think it's possible to configure Win8 to look more like Win7. Too risky for MS to NOT provide the option.