I have a GFCI outlet in my powder room that needs to be replaced. Is it significantly more difficult to replace a GFCI than an ordinary outlet?
No, but you do need to identify the "line" (supply) and "load" (additionally-protected portion of the circuit, i.e. downstream outlets) cables. If they're connected to the wrong terminals the downstream section of the circuit won't be protected.
With a standard outlet, connection location isn't important other than maintaining polarity.