it's cool, I guess, but I don't really get the point. You still have to edit properties in JSON. Not a big deal, but if anything it's less flexible than using something like Troposphere. I was hoping there would be an actual UI to make it more obvious what property combo's should be used in conjunction, etc... without having to pour through the documentation.
It also took about 2 minutes to load up a giant existing template, and the visualization was basically un-usable.