Like strace

It's not really right to suggest that the biggest difference between SystemTap and strace is
the GUI.

Strace can only trace one manually selected process or process tree. That makes it less than
useful once you start to involve D-BUS, HAL, kernel interaction, and other sorts of
inter-process communication.

By contrast, systemtap (and FileMon on Windows) can trace a whole system's actions then filter
out uninteresting data.

I like, and use, both.

My point is that the system-wide aspect of systemtap is a vastly more important difference
between it and strace than the Mortadelo GUI is.