First, let's get this out of the way: while I'm not saying whether Vista is good or bad, Vista was a less good product for Microsoft. That's not my opinion, as someone who's known for preferring Linux; it's also the opinion of Charles Songhurst, Microsoft's general manager of corporate strategy. So I don't want to hear any whining from Microsoft fan boys about how misunderstand Vista was and how, by Vista SP2, it was actually a good operating system. It wasn't, it still isn't, and Microsoft knows that as well as I do.
That said, if Vista is working for you, good for you. You don't have a reason to move to Windows 7.
But if you're unhappy with your Vista's computer's performance, or you find Vista's worst five features ticking you off, then you should switch. Personally, I find Vista's UAC (User Account Control) as enjoyable and useful as those speed-bumps on some streets that make you slow down to five MPH or take a chance on leaving your exhaust system lying on the road behind you.
As Microsoft itself (again, not me!) observes, if you're a heavy-duty user with lots of programs and files, moving from Vista to Windows 7 may take you more than 20 hours. That's not a misprint. Microsoft said, and meant, 20 hours.
The best upgrade you can expect, according to Microsoft, is just under an hour and a half. You'll excuse me if I don't think it will go that quickly. I can upgrade systems that fast, but I install new operating systems and upgrade systems on a weekly basis. I think an ordinary Joe on an average PC can expect to spend most of the day on moving from Vista to Windows 7.
I've also had some people write to me with the misleading contention that if you do a clean install that is delete everything on your Vista PC and then install Windows 7 it will take far less time. They're right. Installing the operating system alone will take far less time. What they don't mention is that you'll then have to reinstall every application, replace all your files, and reset every one of your settings. This will save time? Yeah, sure it will.
In a business environment, you may want to a clean install anyway, rather then tie down technicians to a PC-by-PC chain gang. For this slow, semi-automated slog, I recommend using WAIK (Windows Automated Installation Kit) and System Center Configuration Manager, once the Windows 7 versions are out to ease your Windows 7 deployment.
But neither of these utilities is of much help for small businesses or individual users. Either way, you're still looking at a lot of time. This is no "do it over the weekend" migration for even the tiniest SOHO (small office/home office).
Is it worth it? Is there some single feature that makes it worth moving from Vista to 7? I couldn't find one for moving from XP to 7, and I can't really do it for shifting from Vista to Windows 7 either.
But and this is important even Windows 7 RTM is far faster, more stable and tends to have fewer glitches with older hardware and software than Vista SP2. So, a single 'feature?' No, there isn't one but Windows 7 simply does everything Vista does, except better. Make the move. You'll be glad you did.