Summary of pros (+) and contras (-):
                             serial ISD     monitor
extra chip area needed            -            +              
speed penalty                     -            +
interrupt occupied                +            -
RAM/stack/code space occupied     +            -
vonNeumann code space needed      +            -
single stepping, stop&run         +            +
resources inspection              +            +
breakpoints                       +            -
traces                            -            -
PC application needed             -            +-
correctable                       -            +
pins occupied                     +-           -
various interface possible        -            +