@J-Golden
It's not so much that its great (although most people tend to like it once they delve into it), just that it's become one of the defacto gui toolkits used for amiga os, and as such a lot of software uses it for thier gui functionality.
You can run it without paying anything still, just some of the more "advanced" options arent user defnable, and as such a person will be a little more limited with what they can customise to thier liking.