Revelation is not nearly as useful without the panel applet. It should be installed by default. Failing that, the user should be prompted to set up the panel applet on first run.
Furthermore, the preferences for the panel applet (file to open, default action, etc.) should match the revelation application preferences. I set up my preferences and then installed the applet only to find I had to set essentially the same preferences again.
Basically I would like to see better integration between the application and its panel applet.