they worked just fine for me.
The dozen or so Mantis bugs would disagree with you there.

That code had/has a ton of memory related problems causing everything from leaks to corruption to crashes, not to mention the rendering issues. I never got it to work properly for me, and many others had the same experience. Any time that it did work it was basically a fluke.
I think that Bobboau wants to do a better job with it anyway. Something about an updated POF format, and the additional of the materials system, should make decals work both properly and efficiently.