I used to use the GPL license to license my software, but now it seems like it is too much of a legal nightmare, so I've stopped using it.
GPL is a nice idea...but you need lawyers lots of money and time. I hate lawyers and i don't have time for that bs nor do it have/want money to spend for lawyers, i was a diehard gpl evangelist in my 20`s, now it's BSD/MIT/ISC (and not diehard anymore...more like IDGAS)...and i really don't care for religion anymore...just quality and real freedom.
The freedom that GPL is about isn't about the developer's freedom to do whatever they please but about the user's freedom from the developers' whims. This isn't some arbitrary nebulous religion-like dogma but comes from the very practical issue of developers inherently having power over the programs they write and, by extension, power over the users who rely on those programs.
Remember that the entire free software thing didn't start because the Emacs god visited Stallman in his sleep but because he was denied access to the source code that would help him fix his lab's printer.