I have a java web start app that I use and love (Bill Shubert pwns u
Basically, Bill's app allows you to use it as an applet, or as a webstart app. The applet is very convienent. There's nothing to install, no worries about "wtf is this JRE thing" for the user. Just click and go and the applet runs. THAT'S what I want, because I found the user experience to be excellent when I used Bill's app.
Now of course I've installed the full JRE and webstart apps are no worries for me, but not all users have webstart installed. Thus I'd like to support applets too.