I as a DM have used Sunder to great effect on three separate occasions, and even though it was my players that suffered from the dickery-fest that ensued they totally loved it.
The first occasion was when the dwarf in the party made his first master work item. He whipped it out for it's first combat and the villain he was facing destroyed the shaft of the weapon. Not a permanent blow but it disabled the weapon for the combat. I didn't do it to be spiteful, in fact I had set a ready action and the poor dwarf just happened to be a target.
The second occasion was when they were facing down a group of evil monks. The paladin of the party, wielding a spear, rushes this monk. She disarms him, snaps the weapon in half, and then proceeded to beat the dickens out of him with his form weapon-now-turned-beating sticks.
The third occasion was by a demon. The demon was gloating and laughing because they couldn't hurt him (thanks to DR). When one of the PC's finally did get through, the Demon was very surprised so he promptly destroyed the weapon.
The party eventually defeated the demon but not before he whomped the tar out of them. He is forver remember as "That demon that broke my weapon".
All of my players have given nothing but positive feedback on each occasion, because each circumstance "made sense".