For me personally, the biggest positive thing about Win7 is that it is the Windows OS that seems to finally move home users to a 64bit OS. About time.
Too bad developers still haven't, but then, most things don't really need the 64bit precision or extra memory.
I think Vista would have given you a more 'wow' feeling than 7, which is basically an improvement of Vista, but didn't bring much new (well, compared to Vista) to the table. Too bad driver developers failed so bad with the new driver model, otherwise the OS would have been remembered as good, by the general public idiots (idiots because they thought Apple's ads really represented the situation with Vista), at least.
8 will bring another 'wow', even though most things are really hidden behind the whole 'I hate Metro' crap.
EDIT: I expect 9 to be an improvement of 8, and 10 to bring a lot new features (including setting the new ReFS file system as the default one).