I've been testing Win7 and I think it's a fine product. Early adopters will snap it up, and eventually corporations that avoided Vista will switch to Win7.
But in the general consumer marketplace, I think upgrade sales of Win7 may well disappoint. I think the vast majority of home users will ignore Win7 (unless they buy new PCs).
Why? Well, with any technology, I apply the "good enough" test.
For example, audio: Vinyl was good enough for audiophiles, but for the masses? Nope. Too fiddly: all that cleaning, getting up to change sides, scratches....bleh. The mass market wanted portability, ease of use and decent sound. CD passed the good enough test with flying colours, audiophile gripes notwithstanding. SACD and DVD-A were doomed before launch.
TV? CRTs failed the test. They dominated the average British living room to an uncomfortable extent once you got to 28". Flat screens were always going to succeed.
Video: VHS was obviously not good enough, for too many reasons to list. Neither was Laserdisc (size, turning discs, no record facility). DVD? Passes the good enough test. Portable, fairly rugged and with video and audio quality that defy criticism for the average user. Blu-ray proponents beware. As SACD showed, early adopter enthusiasm is not enough.
Windows OS: Win98SE was okay for its time, but you didn't have to be a tech genius to see that XP brought a whole new level of sophistication and stability to your home PC. Particularly since SP2, XP has been a robust OS which does everything the vast majority of users need. The user base is also vast, much bigger than the days of Win98, so software developers will offer XP versions for many years to come. Crucially, in the Win98 days, a home was lucky if it had one PC. Now many homes have more than one. The proposed family pack upgrade would have to be priced very competitively to make it a serious option. XP passes the "good enough" test. XP was a giant leap. Win7 is gentle evolution. After the initial early adopter euphoria, Win7 has a fight on its hands. It may well rely totally on new home PC sales and corporate adoption.
Will I upgrade? No. We have four home PCs. Even if I had bought during the brief £50 upgrade offer, that's £200 just for a new OS. That's before we talk about essential software and hardware upgrades. Doesn't begin to make economic sense.
When I upgrade the home PCs, it will probably be Linux. Every year or two I run a test installation, and every time I say "not yet". But it's about 18 months since my last test, and
Mint looks interesting...