But you can choose "Windows Classic" as a style in Windows 7 and it will not to be too different, although some thing may be annoying.
For example, Windows 2000 was more keyboard-friendly. In Explorer, you edit the path on the top input, then you tab and you move between files. Since Windows XP that has been increasing, and its 5 tabs in Windows 7. Pratically unusable
The control panel is not yet fucked up like in Windows 8+ but still you can guess the year in which the entry was written.
On the other side, the start menu is better because you have a search field that works well (no web stupid web searches there).
But Windows 2000 was solid as well
There was also some tiny difference between the active window colors as well, IIRC.