I have looked into many a J2EE file upload handler. Just started playing around with commons and I am fascinated by the quality of this software. It's well designed and well written and it looks much better than the other (struts) upload handler put out by the jakarta project.
Though I really hate struts I decided to build a progress bar for struts upload in addition to the one for JSP upload. With in the next few days i hope to put one out for commons as well. Of course all this is part of the mega upload project.