As commercial software user, I don't have much issue with it, after all I have been coding since the early 80's.
And in spite of it and my occasional Linux rants, I am thankful for GPL, because without it there wouldn't be a UNIX to install at home to get my university work from DG/UX done without having to spend one hour traveling into the campus and fighting for a terminal.
Without Linux + GNU based userspace, the commercial UNIXes would all be around.