So far, the most common way to change the generator meta tag is to modify the index.php file of your current template. But if you change template then you will have to modify the new index.php file again. Set Generator Tag does not depend on templates nor it modifies any of their files. Feel free to change as many templates as you want. The generator meta tag will remain intact.
Another way to change the generator meta tag is to modify a Joomla!'s core file. But by doing so you are risking of losing the modification when you upgrade Joomla! to a newer version. No more worries with the Set Generator Tag.
Plugin has been updated to be compatible with Joomla! 2.5(.4). Please make sure that you download the correct file for your version of Joomla!.
A tip for you:
If you leave the Generator tag field empty, then no Generator meta tag will be shown in your site's source code!
I am glad that everything went fine! If you have any comments or suggestions for future releases do not hesitate to contact me.