Personally I adore keymaps! I use them for everything, the main reason is that it allows you to keep your main keybinds constant between all clients.

I can bounce from my pally to my mage to my other mage and know that 6 is the hotkey for a specific skill/button, nothing complex or convoluted.

Yea, it took a bit to get setup right, but once I got that dialed in, rock solid.