Initially Swing Explorer looked like it was the one size fits all solution to replace QTP.
Ok, I was a bit nieve, its more aiken to the Object Spy of QTP, allowing to see the heirachy of a Java object just by clicking it.
The neatest thing it has though is a Player to help diagnose the drawing an layout of your objects. I thought this was a player, ala QTP recording and playback, but no, its a different kind but still very useful if you are trying to debug layout in a Swing app.