The $15 upgrade is only for people who buy a new Win 7 PC between now and the end of the year. If you already have a PC, it will be more like $100 for the Professional edition.
Don't get me wrong, I'm trying Win 8 right now and I like certain aspects of it. I don't think it breaks anything important, either. But when I'm in desktop mode, the experience doesn't feel all that different from Win 7. Ribbon in Windows Explorer? I don't care. One-click wipe? I don't think I ever messed up a Win 7 install. Other changes are rather distracting (oversized window titles and excessive color saturation in various UI elements) but I could get used to it. But the bottom line is that it doesn't feel like it's worth $100, especially since I'm not in the business of making Metro apps.
Don't get me wrong, I'm trying Win 8 right now and I like certain aspects of it. I don't think it breaks anything important, either. But when I'm in desktop mode, the experience doesn't feel all that different from Win 7. Ribbon in Windows Explorer? I don't care. One-click wipe? I don't think I ever messed up a Win 7 install. Other changes are rather distracting (oversized window titles and excessive color saturation in various UI elements) but I could get used to it. But the bottom line is that it doesn't feel like it's worth $100, especially since I'm not in the business of making Metro apps.