I'm still running Vista on my laptop from 2008. It was a little shaky at first, with 2 or 3 blue screens of death, but I haven't had a problem for at least 3 years now, and I prefer the layout to the Windows 7 layout.
I think that people hate on Vista as it was a poor product when launched, and got a poor reputation. Microsoft fixed the issues, but most people had already written off Vista, and then jumped to Windows 7, never looking back and still thinking that Windows Vista was a horrible OS.
Just my £0.02