I still use XP because I haven't had the money to upgrade properly. My experience with Vista and 7 has been on work computers, friend's computers, etc..
xkcd has it covered as usual - I got used to launching stuff very rapidly by hitting Winkey + R + command + Enter. If I had to launch paint, mspaint. Windows update annoying me in the middle of a game? sc stop wuauserv.
Now the run function has been replaced with a "search bar" where I have to filter through a list of things when I already know what I'm looking for. (The names of these commands haven't changed since Windows 95, probably earlier.) I can't just rapidly launch command prompt and have it work because it'll hit a permissions snafu - I have to run as Administrator and authorize that via UAC because far too many idiot users installed bad crap on their computers and Microsoft compensated by adding in safeties that are good for your average end user but completely unnecessary for me.
Firefox has done the same thing. Oh hey, we're gonna add new functionality like tear-off tabs! Also, we're gonna have no actual option whatsoever to disable a feature that you may not want. People should not have to code extensions to disable stuff like this.
I'm a firm believer that if functionality existed previously (barring an extreme example like the xkcd comic), you should be able to restore that functionality. I'd get it if stuff was unnecessarily cumbersome due to legacy support (like how OSX made a lot of apps incompatible), but this is all really basic UI support that shouldn't take an inordinate amount of time or resources on the developer's end to continue to support.