The installer claims to be at step 6/7, however there are only 6 panels defined - one of which is skipped (you may have noticed numbers jumping from 2/7 to 4/7).
This is probably a bug in IzPack, although I couldn't find a matching issue
As a workaround, I have added a finishing panel. Now the count ends at a confusing 7/8, but at least the installer will say that it finished.
Also I disabled writing an uninstaller (just delete the app to uninstall it) and allowed Java 6 for the installer.
Hopefully this helps a bit, try a snapshot build
to give it a spin.