Using the GPL means you're free to use my code ... As long as the result is under gpl too. You lose your freedom to chose a license. You lose your freedom to keep changes to yourself if you release the resulting binary (why ? because you want to). You lose your freedom to use other piece of code that are not gpl compatible.
I have nothing against the gpl and I use tons of software using it, but it is a fact that it cuts down some of your freedoms compared to other licenses.