ShieldsUP is a DDOS waiting to happen. (Or not waiting at all: who knows?)
(Its usage is also against the AUP of most ISPs - portscanning anything for any reason is usually verboten. You probably won't get caught, though.)
But hey, it's EASY, so therefore it's GOOD.
Gibson knows loads about hard disks and next to bugger-all about security.
I don't genuflect before his image.