The only annoyance is that it doesn't seem to distinguish between window types so, e.g., in GIMP in multiple window mode it also cycles between utility windows like the toolbar, options, etc instead of only the image windows - though some applications do not even bother providing window hints about their window types.
This is simultaneously one of the saddest and funniest things I've read about GNOME in a while (which has a surprisingly high bar on both accounts)
Settings -> Keyboard -> View and Customize Shortcuts -> Switch windows -> Alt + Tab
gsettings set org.gnome.desktop.wm.keybindings switch-windows "['<Alt>Tab']"
gsettings set org.gnome.desktop.wm.keybindings switch-windows-backward "['<Shift><Alt>Tab']"
gsettings set org.gnome.desktop.wm.keybindings switch-applications "[]"
gsettings set org.gnome.desktop.wm.keybindings switch-applications-backward "[]"
So if you work in an IDE, keep reading docs in one Firefox window and test your application in another Firefox window then in KDE or XFCE or another sane windowing system[1] - even Windows - you just use alt - tab.
On Mac you have to stop an think: Should I switch to another browser Window? Ok, that is CMD - backtick. Switch to or from IDE? That is CMD - tab.
Press the wrong combination? Now Cyberduck has entered the mix.
[1]:I was about to write Windows or Linux but starting with Unity and now also Gnome has copied this to be bug comptible with Mac