Well, consider that Vista was being developed actively up until SP1, versus Windows 7 where development ended with the RC. During that time the competitors were able to gain additional market share, most notably OSX. I'd say M$ has learnt a valuable lesson, that much is evident in Windows 7.
The reason it seems so familiar is because M$ has a history of fixing up old code and re-releasing as something new.
95 - 98 (win)
98 - ME (fail)
The w9x codebase is a separate development branch from NT as far as I recall, so..
Win2k - XP (win)
Vista - Windows7 (win)
Now Windows 2000 wasn't bad, but XP definitely fixed a lot that was broken. I just cannot see M$ making the same mistake twice here (as they did with Vista), with OS being their bread&butter. It's clear what they attempted to do with Vista, they lacked the resources to produce the final product and tried to get the customer to pay for it. If they do it again.. Well it's not like you have to pay for it.
I really hope this isn't a trend M$ is starting with releasing a crap OS, then finishing and releasing the real deal.
Nope, not a trend starting

(and yes, I left out server influence here)