http://www.eweek.com/c/a/Windows/Vista-Born-Broken/

...the New York Times reports that included in the documents that Microsoft was forced to turn over to U.S. District Court Judge Marsha Pechman was one from Dell, which was aptly named, "Windows Vista Post Mortem." In this March 25, 2007 document, Dell states that the "Late OS code changes broke drivers and applications, forcing key commodities to miss launch or limp out with issues."

In the document, Dell went on to tell Microsoft that its Vista "upgrade program needs a complete overhaul" and that Microsoft should "not change program requirements after release to OEMs as changes are costly, time-consuming and distracting."

...

Even inside Microsoft, we now know that it realized after Vista was shipping that the OS wasn't really ready for prime time. A personal favorite of mine is Mike Nash, e-mailing the crew on Feb. 25, 2007 that "I personally got burned by the Intel 915 chip set issue that I bought PERSONALLY (eg with my own $$$)." He went on, "I know that I chose my laptop (a Sony TX770P) because it had the Vista logo and was pretty disappointed that not only wouldn't it run [Aero] Glass, but more importantly it wouldn't run Movie Maker." As it was, Nash felt that he now had a "$2,100 e-mail machine."