I don't think it is quite the same as spackling compound.
This is from the instructions:
"Poly Instafil ® is a ready to use patching compoundthat will repair large holes in one application without shrinking cracking, as well as smoothing out surface imperfections. This filler is vry effective on drywall, plaster, wood, masonary and concrete. Poly Instafil ® has a very light texturewhich makes it easy to use on wall and ceiling damage where application and sanding might be difficult. Paintable and stainable. Not for busy or high traffic areas such as floors or hallway corners."
It also doesn't "puff" out of the holes like plaster does in drywall during the drying process.
Here is a shot of my patch job. Pretty sloppy, I know, but if time were taken to patch properly, I think it would be seamless.