GUIs already exist in GCMUtiltiy (to shrink) and GC-Tool (to view the files). I make it mostly as I learn a little bit about the Gamecube, and I prefer the command line. Command line tools are the best way to set up scripts and such to automate several tasks.
There's nothing to be afraid of, it's just a little typing...
Oh, and a general note about using this to shrink the files. I have found a few instances where it creates a file different from GCMUtility's shrinker. On one test, it didn't want to run properly, too. I'm still looking into how (and why) GCMUtility does what it does. If anyone else knows a bit more about the file tables and such of GCM images, let me know...