I use the command line all the time. Even for launching programs it's much faster (for me) to just type the name than opening the menu and looking for the program, and then looking for the file I want to open.
"acroread file.pdf" is better than the above.
"ls *-min.jpg" is better than opening a file manager and setting some filter.
"rename Image- Image-0 Image-*" is much faster than selecting the files one by one, clicking on "rename", place the cursor after the hyphen and add a 0 (or searching the net to find a program that would provide a GUI for mass renaming).
But I also use the GUI in Opera and Gimp all the time
