"FreeBSD, that's what the Darwin kernel is based on, is Unix and it's generally viewed as one of the more stable Unix implementations. Add the Macintosh window manager on top of that and you've got the power of Unix and the pleasure of the Macintosh."
First issue: Mac OS X's design for heavy reliance on the mouse. This frustrates my N.A.D.D.. A mouse is swell, a mouse gives you precision, but it does not give you speed.
Second issue: Window management. The concept of "maximize a window" appears to vary based on application. Maximizing to fill an entire monitor isn't a no-no, it just doesn't do anything useful except make the window bigger... kind'f.
I solved both issues incrementally. For mouse and application launch issues, LiteSwitchX gave me my task switching while LaunchBar gave me speedy access to applications for both launch and selecting. Since Jaguar, Mac OS X has taken a stronger keyboard stance by adopting Alt-Tab as Apple-Tab in Panther. With Tiger, Spotlight appears to be landing an integrated means of finding/launching applications.
maximized_windows_everywhere tendency has just not translated Mac OS X, but, two years later, I think I've accepted the transition.
http://www.randsinrepose.com/archives/2002/07/19/two_weeks_of_os_x.html Rands In Repose: TWO WEEKS OF OS X