From Scott on email:

I have used this tool a couple of times recently and have a couple of comments. One, it produces one sld file for all layers in your arcmap project. This means for geoserver, I would go in and break up the one sld file into individual files for each featuretype. But this wasn't that big of a deal. Second, it doesn't seem to handle true-type fonts. We had point layers symbolized with true-type fonts in arcmap and the symbols came in as simply a brown circle in sld. Besides that, it seemed to do pretty well with other symbology and seemed to be a good starting point for getting arcmap symbology into sld.